wow, that's horrendously expensive at $640!! the C20XE is obviously a more widely used engine but a DCOE manifold for them is like £160!
maybe you could build the first XE S12?
150bhp stock, will push 200bhp with milds cams and carbs. only problem would be mating it to gearbox but i'm sure a Ford Type 9 XE bellhousing could be modified to suit.