I agree, that is a load of questions!

I think the answer to all of them is:

Keep the 6.

DCMatt

On the pedal issue. I really like the floor pedal look and would like to retain them if it's at all possible.

1) Front suspension is the same or related to the C1 Corvette, correct?
Yes, very similar.

1a) Therefore a set of V8 motormounts should work with that suspension, obviating the need to use the Mustang II unit.
Nope, stock C1 V-8 mounts are unlike anything else ever used on a Chevy. If you haven't seen one, there is a kind of saddle that runs across the front of the engine and is sandwiched between the water pump and the block. The ends of that sit on brackets attached to the frame. The only other mount which is even close is the Hurst aftermarket unit.

1b) Therefore Rams Horn exhaust manifolds should work if mounting a smallblock because these were OE on the C1.
Nope, the position of the engine relative to the steering box is different. Stock 55-56 manifolds (these are not rams horns) will clear, and I have heard of success with some of the later "under-the-plugs" type manifolds, but I don't have any specific details about which ones.

1c) Therefore there will not be any interference with the stock bell-crank steering setup. (I'm probably dreaming on that last one.)
Normally there are no problems clearing the linkage. It's the box you need to worry about

2) Rear axle is closed drive and will therefore need to be modified or replaced. The '48-'54 pickup axle can be modified with a '55-'64 truck center section to eliminate the torque tube. Is a similar operation possible with the passenger car axle?
Yes, but you don't want to do it. A 53-55 Vette center section will bolt into the housing, assuming you can find one. You will still have to deal with the swivels on the stock spring mounts (take a look, if you haven't already).

2a) Can Eaton Spring or someone make a set of leaves capable of taking the rear axle torque or are traction devices pretty much a necessity with the change to open drive?
You can get springs that will handle the torque, but properly set-up traction bars would probably be ride-friendlier if you have any serious amount of engine output.

2b) If modification of the OE axle is impossible, is the '68-'74 Nova or '67-'69 Camaro axle still the best swap?
2nd gen Camaro is correct for perch spacing. 1st gen is correct for overall width. A 55-57 axle is correct for both, but these are getting scarce. Cheaper and easier to find than any of these is one from a 4WD S-10 truck (2WD is too narrow). You will have to move the perches on this one.

2c) What changes to springs or perches are necessary?
None on the perches if you get a 2nd gen Camaro or equivalent Nova axle. Stock springs won't handle anything more than a very mild engine or gentle driving. They are also rather flexible laterally too.

3) Assuming the V8 is side-mounted a transmission mount will be necessary, correct? I really doubt a TH-350, Muncie, etc will bolt to the OE 3-speed or Powerglide mounts, they were probably bellhousing mounted like the tri-five gearboxes.
These cars all had a rear transmission mount. It will probably be too far forward for most modern transmissions, but you can get an aftermarket replacement crossmember or modify the stock one.

3a) Who makes one? Will I have to fabricate/modify something? Is there a junkyard swap possible?
Look at Chassis Engineering and Walton. I believe there are also other vendors. No junkyard parts that I am aware of.

4) 12V conversion will be necessary because all Chevrolet V8s use a 12V starter, but that's another relevant post.
Yep, no easy way around that one. You could probably have a rebuilder make you a custom 6V starter, but V-8s with any kind of compression just don't start well on 6 volts in cold weather. That's why GM went to 12V on their V-8s in 1953 and everyone else followed not long afterward.

5) Is an aftermarket radiator a necessity or by some miracle do the outlets line up and the OE unit is up to the task of cooling a mild V8? Does it have to be relocated or will something bolted in the stock position clear a mechanical fan?
I have used the stock radiator on my swaps without any heating problems. The stock location will easily clear the fan on a short water pump.

6) Assuming the swap is being made from 3-speed to 4-speed how is clutch actuation best accomplished if one wants to retain the floor pedals?
See my earlier post from today.

7) What modifications must be made to the firewall?
The two vertical ribs will have to go and the handbrake has to be relocated to the other side of the steering column (or the floor).

7a) The heater?
The Deluxe (fresh air) heater will have to go. The economy heater is no problem.

I am interested in doing the least invasive V8 swap possible on a '54 Chevrolet but would be interested in anything relevant to all of the passenger cars '49 to '54.

Thanks,
Dave