Its easy with em, 340s you use Renault engines as they bolt straight in (there a good few 1.7 turbo or Clio 16V/Williams engined ones in the UK), or you do the traditional Sweedish (and more sensible IMO) route of buying a 360 then pretty much any Volvo engine goes straight in.

If only I could read Sweedish, as their Projects forum has some mad shit going on...
http://www.300power.com/forum/index.php?board=17