I agree if your running now and are up front 15 lb heavy, I'd be adding the xtra 25 lb & switching to methanol . If your just starting out knowing you'll be at 375 lb and have the gas motor I'd start with that.
I don't think the performance difference is all that much if the engine is built/tuned for the different fuels.
However, the weight could certainly be an issue, depending on the track configuration (a lot of rpm scrub in the corners vs momentum and little rpm scrub.)
Generally, I'd agree that with you being over on weight already, jump up to the higher weight bracket and methanol fuel.
I aim for being about 4 pounds heavy at the scales.
Thanks for the input everyone! I Have been competitive for the last few years scaling at 400# with no, or very little, weight added. Really cutting back and eating properly and lots of exercise has me 25# lighter than I was 3 weeks ago and I was just wanting some input on whether or not to bolt lead all over like the little guys have to . It is a track with a lot of speed scrubbed off in the corners so I guess I'll scale both ways and see which is better, it's not too hard to switch carb and tanks and bolt the weight on.