Thank you for the kind words!
Your P51 has a totally different reed setup than the smaller saws. Because you have a different set up, it looks like to my eyes when looking at the IPL that you may have room for a 4 reed pyramid setup like the Poulan 5000 series of saws use. the Homelite Super XL saws also used a 4 sided pyramid reed block. I have one of the Homelite units that I used on a 4 cube Remington engine of mine.
IronHorse recently posted videos of his hotroding a 51 or 52, he used the stock block and a thinned fiberglass reed with no limiter/cage to confine it.
Go for it! New blocks are available so go for broke!
Yes, the reed blocks are quite different on the smaller saws vs the 5- and 6-cube saws, although they use the same reeds. But it doesn't look like a pyramid reed would fit into the curved space that's the same shape as the stock reed block. I'd love to make something bigger work, especially on my bigger saws.
You inspired me to do some more obsessive tinkering on my Pioneers while I was waiting for some work to show up. I am indeed obsessive about my saws and chains. I checked to be sure they all had the shorter, curvier limiters, and they did. (I remember bending one for more curve a long time ago - it may have been one of the longer ones.) Also, in looking at some of my old parts, I saw that I had reamed out several blocks at different times. They were more prone to cracking, of course.
I ended up leaving the P52 and 655BP as they were with essentially new reed blocks. Re-sealed the reed blocks and vac tested. I'm wishing now that I had done at least a bit of reaming while I was at it or swapped in some old reamed-out blocks.
The one on my P45 is like a P42, P41, etc. I noticed that the Boyesen reeds weren't sealing very well. Using fine sandpaper on glass, I flattened the reed sealing surface on that one and another one I had handy. The second one had been reamed, and I put the saw back together using that one.
The P45 hasn't idled well for a long time. It's ported to run like a turpentine cat (as are my bigger ones) and has a fairly large modified carb, so I was thinking that's just how it's gonna be. I'm waiting for a reason to fuel it up and run it and see if it's better now.
I've never tried putting one together w/o a reed limiter. More obsessive tinkering needs to happen. Thanks for making me think.