RE: Engine compression..How much?
I got mine at walmart for $20...
if the engine is not ran, IE fresh ring (you said you just got a big bore kit) the compression will be lower than after it is broken in, if it's that low, add some oil through the spark plug hole before trying to start to help the compression some. also, it depends on how you were testing compression, most say to pull the cord 5 times (a good 10 or so compression strokes)
as for just general compression, 120+ is normal and in good shape, around 90 is getting on the tired side but will run fine, 60 and lower most likely won't run at all usually means a stuck or broken ring or the piston and cylinder wall is scored...