I just bought a KN Laser but I would like to know if a rwd conversion can be done and I'm not talking about putting the engine in the back more n/s engine conversion to rwd or maybe an awd conversion I would like it if I can squeeze a 2 litre from an SR2 or SP20 or maybe a small v6 maybe from a late model Telstar or Mazda

Short answer, no.
Long answer, with enough money and engineering expertise, anything is possible.

I'm sure with a little engineering and modifications a rwd conversion could be done but then everything does add up engine mounts and other mods front suspension and steering tunnel rear axle diff and suspension set up bigger discs and calipers bigger wheels and tyres drop in a bigger 4 cylinder add a decent turbo and maybe an added small supercharger to spool up the turbo good ems bigger injectors mild cam flat top pistons strengthened crank conrods main bearings extractors 2 1/2" exhaust the body kit roll cage bucket seats.......................Yeah I see where this is going lol $100,000 later but hey the thing would be a beast! I could probably get someone down at FPR/Prodrive to build me something for that kind of money question is would it be street legal? But I guess I'm only dreaming lol!