contact Josh at kentucky turbo.He has great feedback on ls1 tech. he runs a one man shop and has been building turbo's for the f body crowd.I believe is doing a big block chevy in a 69 camaro at present. He is great to talk to and will shoot you straight on figures and questions.
If you can't weld and fabricate and have all the tools, it's not going to be easy or cheap. Nitrous is you best dollar per hp power adder with complete kits going for less than $500 gaining at least 100 hp.
i had the weiand 144 and it was awesome crazy power . but crazy money 2 you can get a used one from $600 to $1200 just got to find them . also make sure that its not scratched inside low boost levels .. works best on stock to mild builds low comp heads work the best . like 8to1 or 9 to1
ive seeen "twin turbo" kits on ebay for like 900$, it had headers,bypass vales,intercooler,carb hat, everything except the down piping, they say you get what you pay for but id look into it if i had the money, wouldnt hurt to check it out?
nitrous is the best bang for the buck, but i prefer turbos or superchargers, you dont have to refill them lol