Power washing bare block?
 

I'm looking to clean the oil/coolant ports on a cast iron 350 block. I'd rather not pay the $80 to have the block tanked... I have access to a hot water pressure washer.

I have the freeze plugs out of the motor. If I am to spray the crap out of the motor, dry it and oil the cylinder walls, valley, mains, lifter bores, bolt holes and everything else with a machined surface will I be okay? Do i have to worry about the rough surfaces (like coolant ports/inside of block) from rusting or having to preserve them with oil/WD40? The motor will only be out of the vehicle for a few more weeks after this.

Will not do a good enough job. You need to clean the inside of the block too.

And a commercial hot pressure washer won't do that if I spray through the freeze plug ports/top of deck?

I do not think so, no.

You could probably get away with it but if there is crap in the cooling system you are going to kick yourself.

Well then I suppose I'll just cough up the $80 and have it tanked :(

I dealt with a motor that was not tanked upon rebuild and it had cooling issues. YMMV.