While it is theoretically possible to fit just about any engine into any car, the main consideration should always the purpose of the swap, and even though engines such as the RB26DET, 2JZ, LS1, SR20DET, and almost all their variants have achieved iconic, if not legendary status because of their proven reliability, and suitability for motor sport applications, fitting one of these engines is not always the answer.
Fitting successful engine is seldom enough to make a car successful, or even competitive on the racetrack, and factors such as transmission, final drive, weight distribution, wheelbase, suspension setup, and track width all play important, if not decisive roles in determining the success of a competition vehicle. These issues might not be of overriding importance in say, spinning, drifting, or street racing, but on the track, they could mean the loss of all competitiveness if the effects of a heavier engine on vehicle dynamics and handling are not adequately addressed-regardless of how many trophies a particular engine has won in other cars.
If the only criterion used were the ease with which RB26DET, 2JZ, LS1, and SR20DET engines can be modified and still remain reliable, there would be nothing to choose between them, and while they can all be fitted into road cars equally successfully, the focus should be on what it is likely to cost to get it to work, while retaining reasonable handling.
For instance, the Nissan Silvia S13 is already highly successful on the drifting scene with its original engine, so it would make no sense to replace it with anything else- an exercise that could require extensive, and possibly very expensive modifications to mountings, transmission, final drive, and suspension to regain the competitive edge it is likely to lose by upsetting its dynamics with a heavier engine, like say, the LS1: you get the picture, right?
It is not possible here to provide even ball-park figures on what various engine swaps, and their attendant modifications are likely to cost because of the large number of variables involved, such as the make, model, and year of the base vehicle, the desired engine and its state of repair and/or modification, and the intended purpose of the engine swap.
In most, if not all cases of engine swaps, the final cost is very unlikely to be less than the cost of a vehicle that already contains the desired engine, and where factors such as suspension setup, weight distribution, wheel base, and track width, are already in place and proven to work in conjunction with all the bits and pieces that make up a competitive car. Below are some examples of imported cars that can be driven home from the dealer, without having to undergo major repairs or modifications just to get them started:
1969-1979 Nissan Fairlady Z (240z): $10,000-$15,000
1989-1990 Nissan 300zx: $7,000-$9,000
1989-1990 Nissan Silvia S13 (180sx): $6,000-$9,000
1989-1990 Nissan Skyline R32 GTS-T: $7,000-$10,000
1989-1990 Nissan Skyline R32 GTR: $12,000-$15,000
1989-1990 Mazda Savannah RX-7 (FC): $6,500-$9,50o
1983-1987 SPRINTER TRUENO GT APEX: $6,000-$10,000
Of course, these are just examples, and actual prices will be determined by mileage as much as the general condition of any particular car, but the biggest advantage of an imported car is the fact that you get a complete and fully functional car for about the price you can expect to pay for a highly modified engine alone- to which the cost of fitting it to a vehicle it was not intended for must be added.
Thus, buying an import, and rebuilding the engine will give you a car with its handling characteristics intact- which will definitely save you a ton of money, weeks of fiddling, and getting hopelessly frustrated with a car that may never work as well as it could have done without the engine swap.