Oil clearances and a surprise

I hate to say this, but, I would go this route myself, actually, I have gone this route. Take all of your stuff and bring it to the new machinist for inspection and tell him your plan is 6500 shift points. Also that you want tight clearances. Tighter clearances reduce the need for thicker oil. As an example, modern cars run very tight specs and suggest very low oil weights. My son-in-laws Subaru sport ride with a boxstser engine runs W0-20 weight. You also don’t need a high volume oil pump.

I will say spinning past 6500, you should consider oiling mods. Enlarge the feeds everywhere. Starting with the oil holes to the valve train.

Let the machinist start from scratch and line bone the block and recheck the crank. I know this is expensive but skipping the expensive re donof bad machine work only has you spending twice. Once to do it wrong and wreck good parts and a second time to repurchase the destroyed parts and machine everything again.