If you have a garage a kinda high budget and the nesassary tools it shouldn't be too bad. The hardest part is figuring out what you want. You mentioned modern drivetrain, so I assume you mean like a LS swap? The aftermarket has a lot of parts for this swap but if your on a tight budget, you might wanna go kinda oldschool late model or a used drivetrain. I personally have never done a LS swap but have read a lot about them, I bought a couple books on LS engines one is about them the other is a swap manual. For me the hardest part would be wiring and plumbing I think. I could drop one in and bolt everything up without a problem. Also there are a few ways to go with it, a carburator setup, stock fuel injection or aftermarket fuel injection. Don't forget also the front drive system may not clear in some areas this may require an aftermarket setup. First thing I would do is research how much either setup you go with will cost you to do it right new or used engine and transmission, the later model transmissions also require a seperate computer to work properly or you can also bolt an older transmission to a LS with an adapter for the flexplate and longer bolt kit. The engine mounts in the frame will have to be changed also the block mounts will need adapters unless you can modify stock frame mounts to fit your frame the exhaust will also need modification the stock manifolds may or may not work then you will need a set of swap headers,transmission crossmember modify or custom built, a 10,12 bolt Camaro rearend or a Ford 9 inch should work with some modifications and a driveshaft will have to be made to the specific length of your setup. You may also have to modify the transmission linkage if it's an automatic or use a floor mounted shifter. I own a 03 Silverado with a LS it has 210,000 miles on it and still runs very well, in the future I plan on doing a LS swap to one of my other projects, when I can afford the swap parts and the used engine.Hope these suggestions helped.