53 pan top/ 40-47 knuckle bottom

[Lateral1200]

Encouraging news. I was just making another attempt and the front pan tappet block now fits perfectly and the rollers engage just fine with their respective cam lobes (stock lift and duration lightning style cam). Three of the four bolts also line up just fine. I am using Ted's generic blocks for Panhead-Shovelhead 48-up and comparing to pictures on the internet they seem to have more metal from the flange down compared to the OEM style 48-52, and that seems to be the problem with the rear tappet block, there is some interference that does not allow it to fit all the way in, but fortunately it is visible that the four bolt holes line up perfectly. I will therefore give it a try with tappet blocks 48-52, which it seems to me was done on the Rooster/Bigincher’s engine, judging by the picture. In case it doesn't work it might be more prudent to sell the whole thing and go back to my side valves. But I'm cautiously optimistic for now.

[nmaineron]

My 52 FL had aluminum blocks that were worn and broken. I replaced them with later model steel blocks. I don't recall now but I had to grind one of the blocks to make it fit. I had no problem running it after fixing it.

[Lateral1200]

Thanks nmaineron! I'm trying to achieve a more proportionate fitting and I came to the conclusion that the tappet blocks used in the hybrid I'm taking inspiration from used tappet blocks with less metal both on the flange contours and below it, from 48-52. I could try using a Dremel here to rough up here and there what I already have, but I don't think the functional and aesthetic results would look good and it would probably ruin good parts. I have already ordered and should receive them at the end of next month, meanwhile I am researching some questions regarding measurements; solved the issue of tappet blocks remains to know the differences in deck height to determine if I will have a good manifold alignment. Stroker plates or shaving... let's see. I know the stroke is the same but I suspect there's a difference in deck heights, as Rubone pointed. Best regards!