Rick, you might check out Dryad, they have a sale coming up. I have an Orion 15" riser and extra long acs longbow limbs(draw 29.25") as well as a set of ILF acs long longbow limbs on a metal riser. Sweet shooting rigs and I also run a fixed crawl. I can get these quieter then my recurves with a fixed crawl.
A metal riser allows for a plunger, easy to adjust center shot and adds mass. I shoot the metal riser with a springy rest and the Orion off the shelf.
Speak with Mike at Dryad as limb length is very important to match to your draw length. Yes you can adjust both tiller and poundage. Adjusting poundage also effects preload(how much bend in limbs at brace) which effects performance.