It's been awhile since I've done any updates on my work on the Big Twin Flathead oiling system. I've written my previous work with BTSV oiling systems and had them posted else where on the web. I'll include links so that they're easily available.
What I hope to do now is bring this info up to date.
Briefly, (not that I'm ever brief), I like these big flathead motors and from my first one, have had troubles keeping them from melting down, so to speak.
I Turned to adapting the Ironhead sportster oil pump to fit the BTSV, and used the extra oil out from these units to cool and lubricate the big flatheads to keep them alive.
As a point of reference, the '72 and up Sporty oil pump delivers 8 times the oil that the stock pump does. The extra oil is used to supply piston squirters and full flow to the crank. In conjunction with an oil cooler, long, reliable, life can be expected from the big flatty.
That's the background.
While getting extra oil to the motor wasn't a problem, keeping the engine oil tight was. Biggest leaks were the tappet blocks and covers and the oil pump mounting to the engine case.
With the tappet covers, I went to the earlier style screw together covers. I modified them to use O rings at all junctures and in addition, I grooved the tappet blocks to accept O rings A La Sporty, where they fit into the engine case. I also countersunk the case holes for the tappet block mounting screws and used O rings between case and tappet block to seal off the block mounting screws.
In the latest iteration, I soldered a flat washer machined to fit in the top section of the spring cover, chamfered the inside edge where it comes up against the valve guide to take a Viton O ring, added another chamfered flat washer on the outside of the upper cover so that the O ring is sandwiched between the flat washers and no oil can get past at the top. Regular Buna O rings couldn't take the heat. That sealed up the valve cover area.
I made several attempts at sealing the sporty pump to the engine case, and the final version incorporated custom gaskets for all 3 interfaces. (pump cast iron top to engine case, Cast iron base to main aluminum body, and main Al body to bottom pump plate.

The single design parameter that I felt I had to maintain was to use the 4 original mounting holes in the engine case to mount the pump. On a couple of earlier installations, I had oriented the pump body so that some holes had to be moved, but more of the original sportster pump mounting holes could be used. The sporty pump having 6 mounting holes.

The latest version I changed how oil from the supply pump is routed. Up to this time, I had removed the check ball from the "snout" of the pump and used that as the exit point for oil from the pump. However, this meant that the output oil was flowing around one of the mounting studs for the pump. I always had trouble preventing leaks from this area. So, I drilled the area where the stud passed through the pump body oversize and tapped and threaded a solid aluminum "plug" made from 1/2" bar stock, which blocked off that passageway. I then drilled and tapped a passageway that intersected the output from the supply pump closer to the source and thus the supply pump avoided the stud area and eliminated a source of leaks. You can see the place where the oil now exits in the pictures.
Also as a leak preventative measure, I countersunk the bottom plate of the pump where the mounting studs exit so that I could use "O" rings and flat washers on the studs to seal them up.

Updates to the original supply pump body on the latest system

The original supply pump is used merely to distribute oil to where it’s needed. Originally, in addition to sending oil to the Crank, I routed oil to the piston squirters as well. This was done by tapping into the cap that sealed the chamber where the check valve ball for the flow to the original centrifugal oil bypass system(which is disabled). This was a handy place to get a supply of pressurized oil. This did require some reworking of the original pump passages.