would an engine swap in my 1970 1200 coupe from the original to say an sr20 increase or decrease the value now and in the long run?

I wouldent emagin it would make much diferance in the long run and so long as its engineard it would probly increas its value straight up. but thats just a guess.

Nicely done SR conversion in a coupe, would probally give the car a conservative value of $10,000

Deduct the cost of the conversion and see if is a increase in value.

As good clean original cars become harder and harder to find ,good original examples will be the most sought after in the long run, if your car isnt in very original condition to begin with it doesnt matter, but if you spend $12000 to finish your car with the SR and can only get $10000 for it then, it isnt really putting you ahead.

you must also take into consideration that when people do these engine swaps they also generally do a whole lot more than the engine, the cars that are selling for $10k and over generally have been resprayed and the bodies are in very good condition.

My ute is an A series and everything is as if it just rolled out the factory and I love watching all these other cars go for so much because it know that it drags the price up of mine... There was also another little white ute that surfaced a few days ago (in a thread on here) and its a beautiful mostly original example, I would think it would be worth quite a bit.

stock classic cars are worth money in the long run, as long as chasis and engine numbers all match up from factory plates etc. other wise its modded so you might as well go the whole hog and go crazy.

Classic example, VL walky got stolen in Canberra years ago, stock motor stolen and twin throttle bodies, motor turned up agin and owner got it back, missing twin throttle bodies. In the mean time he decided to mod it for a 2jz or 1jz toyota motor.

Which do you think would be worth more to a collector?

Would you pay $500,000 for a modded pahse 3 gt falcon?

If its original but dinged up and not in concourse condition I say do whatever you want to it, but I would be a little more careful if it's original and in pristine condition.

A car can be restored any number of times but it's only original once

Do whatever will bring you the most enjoyment. Plus you never know, you might not be allowed to get certain motors engineered in the future.