There are two sides to this story.
Value now days seems almost exclusively to rest with original examples. Whether an old guy reliving his youth, a hipster making lattes at a cafe using it as a work or promotional vehicle, a cashed up young dude hoping to pick up, an enthusiast adding to his collection, investors wanting to cash in, or a money launderer, they all seem to be looking for original examples, restored or survivors.
Now for 1837's point, there is a great argument to modify basic cars. You wouldn't in sane mind for instance modify a HK GTS 327, or a HQSS, or a GTS 350 of any kind even if they were shit to drive compared to modern cars, hot in the cabin, tight heavy steering and no brakes, and just plain dangerous in the wet. However if you did want a classic car, wanted to improve the driveability and safety, the only sane thing to do is to modify a base model car, or something that is so far from original in the first place that chasing the parts and returning it back to stock trim is to arduous and expensive, and you would like to drive the car this decade.
Thus 1837's argument, best modify it and use it unless you are a staunch purist.
Now look at base model HK Monaro. try to find one especially a V8, they were all modified and turned into GTS copies or parted out for other cars, now you are looking at V8 GTS prices or more if you can find one. Same goes for premiers and station wagons to a slightly lesser extent, unobtainable with prices surging.
Both arguments have merit. If you want to drive it safely, long distance in any weather with mod cons modify it but make sure all can be easily returned back to original and try to keep the original parts. I think the future may rest more towards the original base model survivor cars or restored base models as they are very thin on the ground , all the investment grade popular models are out of reach for the average punter.
I personally enjoy the raw driving experience or no air conditioning, vinyl floor coverings, non retractable seat belts or no seat belts at all, crash box column shift manual, understeer, magma hot vinyl seats in summer, the smell and the feeling of about to roll over at any moment, not for everyone.
At the end of the day its all about enjoying the hobby, modified, restored or original.
