No bore gauge? Shove a piston ring in and check the gap with a feeler gauge. The service repair manual will give you a range to work within, make sure you allow for a crosshatch.
When replacing the oil pump housing or after you've done a rebuild before putting timing covers on and your belts back on, put some oil in and spin the oil pump with a drill, make sure you got no leaks.
It goes the same when replacing the water pump, go ahead and put the hoses back on and fill it up with water, make sure its not leaking.
The moral of the story is check your work as you go!
Feel free to share your engine building tips so we can all learn from 20/20 hind sight. Ill post more of my learnt the hard way wasted a whole day experiences when they happen, i'm only human after all.