Recommendations to repair-not rebuild-a Model A Engine

[Bud]

I just recently acquired a diamond block Model A engine. I removed the head to see what I bought and found the bores only .040 over. The bores look very nice, but the engine, head and spark plugs look fairly black with soot and oily. I have not looked at the head and block surfaces yet, nor have I inspected the main and rod bearings for clearance.
The thought has crossed my mind that if the block and head look good visually, perhaps I could do some service work to this engine without sending it to a rebuilder. I could perhaps regrind the valves, install new valve springs and cam gear (if it needs it), install all new gaskets, generally clean it up and have a good engine as a spare without a big investment.
My question is: what do you recommend in evaluating this engine and repairing short of rebuilding it?
Can I re-use the pistons and put new rings on? How do I determine if the rings really need replacing? Same with the valves. I am interested in your recommendations. Thanks in advance.