Straight swap engines for zxr400

[reds]

been having a look at newer engine on ebay - as figured if i have to do cam chain / tensioners , might as well do all teh gaskets too, and its at least £100 in parts.

so far having looked around i can see that a zzr600 is pretty much a straight swap.

will an l model engine fit in a h frame ?

i have also been told it is possible to fit a cbr600 realtivley easily to - can anyone shed any light on this ???