Slant clean-up and oiling question

Ah that head looks nice & clean!

See here if this link works for you; it haas a /6 oiling systme diagram:
http://www.slantsix.org/forum/viewtopic.php?t=396331

Oil has to pass through the #4 camshaft bearing (like SB). Oil to the top is very slow and has to fill that long rocker shaft. I have to wait 30-60 seconds running to see oil coming out of the rockers holes; #6 rockers see it first, bein' downhill. I never need drip catchers when idling.... but the oil pressure at idle may be a bit low on my 52 year old /6!

Your head casting number matches for 64-66 per this:
http://flag.blackened.net/mopar/slant62.html

That article is not complete on the block numbers. For instance, my '62 block is 2202857-7. I assume you mean 3 freeze plugs; that is the older blocks style as I understand things. Also, your flat oil pump cover and pump casting style is the oldest type too; should have 6 mouting bolts in the housing.