Sending my heads and possibly my intake manifold (depending on feedback) to get the hot tank treatment in order to port and polish my heads and intake. Want to know if it'll be worth it to port and polish them on a completely stock 390.

While I have the heads off should I drill out the oil return passage I feel like I've heard somewhere it doesn't circulate well and pools in the heads.

 

Yes, it's worth a few (and cheap!) HP/TQ to port-match the heads and intake. I'd be leery of having them polished unless the guy or gal behind the die grinder knows what they're doing with FE heads. Use the intake and exhaust gaskets as a template to scribe the outer dimensions and only grind up to one-inch of the intake and exhaust ports. The surfaces need to have some roughness to reduce"laminar flow"- The behavior of liquid against a surface. Too smooth and the fuel vapor (droplets) will stick to the metal while the high velocity air simply shears past... a slightly rough surface creates turbulence and keeps the fuel vapor suspended in the air flow and results in a more consistent A/F mixture.

Port-matching can be done at home... a $30 roll kit, a couple of bits for $50, and a few hours of your time.

Do not "drill" the oil passages in the heads. FE oiling systems actually pump too much oil in the heads and starve the mains. A common modification is to install Holley carb jets under the rocker arm pedestals to restrict the oil and redirect the pressure to oil the bottom end. However, one thing that you can do is to improve the oil drainback to the pan by smoothing the radius of the drain holes... it only needs a light touch to remove the hard edge. In fact, this is where "polishing" would be encouraged.

 

+1 not really going to see anything from polishing ports on a stock motor .
go ahead and port them the finish is pretty smooth ( alot smoother than factory cast job)