^^^That's right!
Here's another strategy. Buy the n/a S1 and don't spend any money on it apart from routine servicing brakes and tyres etc. Save up the money you would have spent on turbos, manual conversion etc towards a 260RS. It might take a few years but it would take a few years to modify your S1. I've been there and I started with a RS4T - better turbo, piggy-backs, then GTR box diff and axles, better brakes, Link computer, better suspension, wheels, seats, RB30, bigger turbo - you get the idea: incremental improvements but with doing some things twice. The total: $50k
Save up for a 260RS ...should be under $20k or even less soon ($12 - $15k over here) and at least you have a good base - RB26DETT, GTR box, brembos etc.