i sold that rs500 a few years ago for £10500 and gave the buyer the original rs500 bottom end as i had fitted an uprated 200 block motor.within 2 weeks or so it was on pistonheads for 17k with no mention of its history.(i disclosed everything about the re-shell/cat d etc when i sold it).also,it seems to have "gained" service history now too!!!
its a funny one as it is an rs500,if its still got its original block with it,so will always be worth something,but it will/should always be bottom end money....whatever that is for one- 12-14k maybe?