Hmm, yeah, that's a difficult situation! What I would suggest is making another copy of LFS with the earlier patch that allows you to use LFS Tweak. I have found that without using Tweak, the XR GT is fairly close to my Miata, and the FZ50 is close to my friends 996 911 GT3 that I've been fortunate enough to race a few times lately. I have another friend with a 260rwhp turbo Miata, and for that I modified an XRGT in LFS Tweak and was surprised how similar an effective driving technique is in LFS and RL. The key with that car is just to keep off the damn throttle! In the sim and RL you can get full power down in 2nd gear in a straight line, but it's sooo easy to overshoot the next turn when you try and use full throttle at every possible opportunity.
Edit: Thinking more about getting something similar to your s2k in LFS...I would think the closest car in the game is the XRT. The weight is not far off, and same with the power. Yeah, it's turbo and has a different powerband than the vtec in the s2k, but overall for practice with autox I'd say you could get it feeling close enough. If you were going to modify something in LFS Tweak I would start with the XRT, and change the engine to be similar in characteristics to s2k (although you can't model the vtec in LFS of course...). Tire width I believe is fairly close in the XRT but you can always change that so it's just right in Tweak anyway.
Edit: Thinking more about getting something similar to your s2k in LFS...I would think the closest car in the game is the XRT. The weight is not far off, and same with the power. Yeah, it's turbo and has a different powerband than the vtec in the s2k, but overall for practice with autox I'd say you could get it feeling close enough. If you were going to modify something in LFS Tweak I would start with the XRT, and change the engine to be similar in characteristics to s2k (although you can't model the vtec in LFS of course...). Tire width I believe is fairly close in the XRT but you can always change that so it's just right in Tweak anyway.