Thanks for the information. I have been looking at the XS274S as an alternative to the XE274H. I have more hands on experience with the hydraulic flat tappet shafts is reason I was looking at the 274H. Never used a solid flat tappet. I assume just a few different install/setup procedures and possibly require revisit from time to time on the valve lash setup?
Only experience on solid lifters was on my wifes 73 Super Beetle she drove many years ago.
Plan to just bite the bullet and tear down the engine while on vacation this holiday week and see what is in there, it has been bored 0.030". Have read that it may be best on stock lower ( cast crank, stock rods/bolts etc) to keep piston speed at or below 4000 f/min. Is that a realistic. By formula I saw on I-net 6500rpm on stock stoke (6.123") comes out to about 3588 ft/min. I will be replacing all bolts with ARP fasteners at a minimum. Depending on how the existing rods check out, may upgrade them as well, we'll see once I get in there and see what the last rebuild folks installed.
Piston Speed (ft/min) = (Stoke (in) x RPM)/6
BTW, did you drive this setup on the street/highway any?