wow if thats out of a compression tester. thats scary...
mattoon machine has a nice anodized billet basket, and all the small engine bolt kits you would need.
you should be able to find a decent pro design head or preferably NOSS cool head. the OEM impeller will be just fine in that motor. they are actually one of the best water pump setups i think. new bearing and seal IF it needs it and your good to go.
just get a k+s seal kit and cometic top end gaskets with OEM clutch cover gsket.. or just OEM crank seals .... then use a new o-ring set IF you get a prodesign head shell you will need studs also.i believe a chariot head would be just fine too.
porting is a whole nother thread.