I found a couple of these left over from a batch I made a year or two ago:
It's a brand-new, from-scratch SI Bushmaster body, bored to take CCI Phantom feed blocks. Everything else is 100% SI and takes Bushmaster barrels and internals.
The only issue is that with the SC feed, you can't use the stock SI field-strip screw for the valve body. You'll either need to counterbore the valve body to take a recessed screw, or use a "buttonhead" allen screw and drill a clearance hole in the underside of the feed tube.
Other than that, it's a drop-in mod. Take all the Bushy parts off and drop 'em in here.
I didn't have these last couple annoed, as I was planning a couple of custom-color guns, but I never had the chance to get back around to 'em. My loss is your gain.
$65 shipped in the US, and I only have two left, so first come, first served.