Fresh Rebuild Losing Oil

[Step'67]

So my dad and I recently did a mild rebuild on a 350 for my 67. Stock bottom end, new cam, lifters, Vortec heads, intake, etc. I was doing it on a slight budget and just went with Summit brand piston rings, possibly the problem. Anyways, dad has done tons of motors over the years, in his own Chevelles, Camaros, a 71 Blazer, he has been around the block and is no stranger to car restores and engine mechanics. However, he has never had an engine use oil, and no where near the magnitude as this one does. It seems to be losing a quart every 2 weeks, possibly sooner, although it does seem to vary a decent amount. It seems to have traces of oil coming out of the timing cover seal, but in very pitiful amounts, no where near enough for that to be the main issue. It is also leaking between the engine and transmission, but on further inspection, the rear of the engine, behind the flywheel is perfectly dry, i think its only the nasty 4 speed transmission (new overdrive from Bowties is on the way here soon). I also installed an oil separator inline with the pcv valve, and again, a very small amount is collected in the separator. Upon start up, a slight amount of smoke can be seen from the exhaust, so we were thinking possibly the valve stem seals, and I've got new ones of a different material I have yet to install. The thing is, with it using that much oil, there is no burning smoke visible in the exhaust at any rpm, after starting of course. However, the oil consumption seems to speed up when at higher rpm (freeway vs town driving). Another thing to add is when ordering parts I accidentally ordered a Melling high volume oil pump, which places the oil pressure off the gauge when cold, and at the very highest point when driving while warm. Sorry, just trying to generalize here, but any ideas on where this oil could be going? We had the cylinders honed and all machine work done at a reputable machine shop, and used high-quality break in oil. Could it be that the Summit cast rings just never seated? It's been at least 800 miles since the rebuild, so I figure they would have already. Any comments would be helpful, thanks guys.