Stock heads/rotating assembly, hot cam/vlave springs- how far can you go?

I did a cheapy 5.9 many years ago, $100 running core with 185000 on the clock. Both heads had cracks Ray Charles could have seen, a few exh guides were a little loose, cam bearings were toast. Everything else looked good. Ball honed it, cam bearings with 1/8" holes, simple valve job, hot pressure washed it all. Reused heads, valves, rockers,oil pump, and rest of short block. Pistons were all 053" ish in the holes. China air gap,Oregon regrind, 1121 head gaskets, hughes springs and retainer kit, pushrods, fuel pump thingy, $35 timing set. Napa cast rearing kit, homemade pan and pick up,spent maybe 2 hours smoothing out the pockets and took 3/8" off bottom of intake guides. Old girl runs like a beast for what it is, kind of wish I would of put valves in it, but didn't want to spend the dough, have a little over $1000 in it with some elbow grease. No machine work except for the valve job. Turns low 6s all the time,(rpm). Really thought it would have spit the bit along time ago.