A 3.5 V8 is an aceptable engine to use. Period correct and will look right in the car. It has about 240 HP so it's just right for the car. 300 would be dangerous in a car like this.
Just a thought on how much work you can get into:
A customer said, '' Here, put this in my car. The guy I bought it from said it will only take 8 hours and you don't have to drill any holes. ''
I knew that none of this would be true because you can't install A/C without drilling holes through the firewall and there are holes needed for evaporator drainage. I said yes but I wish that I hadn't.
After removing the hood, rad, fan, pulleys and a number of other things I started assembly. First thing I found was the fan pulley was rubbing on a screw for the water pump. Take it all apart replace the original screw and assemble again. Now the pulley is hitting the AC bracket. Remove the fan and pulley again and place 4 washers under the pulley to shim it out. Ever try fitting one of those visco fans with 4 washers hanging on the screws?
So we finally got that all on and mounted the AC pump. Turned the fan blades and they were hitting the AC pump. Ground off a bunch of metal on the fan blades until everything cleared...
Installed the rad and then the AC condensor. Had to remove some metal around the air filter canister so the bracket holding the condensor in place would fit better. Finally got the brackets bent into the right shape and had the condensor so it would fit OK. All of this took most of one day.
I had instructions that were idiot proof but this idiot couldn't follow them. It said 'install short hoses ' but they were all short, although they were labeled. There wasn't any diagrams to follow. Called the guy who made the kit and he told me how to mount them which worked OK.
Had to get some PAG oil to coat the threads - that stuff is espensive. I also had to get a 1 3/8'' hole saw for the hoses to run through the dash. Took me a while to find one. Tried to drill the hole and the drill broke. Got another drill and finally got that sorted out. Two days in now, messing with this thing.
Finally got all the hoses in and installed the under dash unit. Had to drill two big holes in the dash and feed the hoses in. Some more holes drilled under the dash to mount that plus some wires to hook up.
Pull the fuse box and somehow manage to get a wire from the blower motor hooked on. Fan runs and AC comes on!
Hook up the dryer but I don't know which way to mount it. The dryer has an 'IN ' side which comes from the condensor which took another call to find out. ( can you tell I know everything about AC? )
Then I have to figure out a way to mount the dryer which is just sitting there beside the coolant tank. A number of plastic tie straps finally hold it in place.
This took a lot longer than 8 hours but looks good and not a sloppy mess.
I think my only point is, even with help and instructions it's still a custom fit and it wasn't easy to do. I still don't have it charged yet but it should work OK.
Anything you do outside of stock aplication can be VERY time consuming and often difficult. Anything you do that's a simple routine job can turn into a huge job if something goes wrong. Ever drop a screw into a cylinder or down into the front of the engine? Maybe twist off a bolt in an impossibe place to work? It all happens and you're the guy that has to fix it.....
I'm not telling you or anyone NOT to do these things. Just be prepared for some hard work. It could be fun and rewarding if it works well on the other side or it could be the worse thing you ever did. Have a picture of what you want firmly etched into your mind before you start. Make sure your goals make sense and that it can be done in a way that works and is safe.
The more realistic your goals, the more it's possible to do.