Yes. There are 1/4" and 3/8" spacer plates that allow a stock style manifold to bolt to the Millennium head (see pic). I used these on a 1800 HP blown alcohol HEMI that ran pretty well but ultimately was flow limited. Stage-V has these.

BTW: I feel I should make a comment about "shooting for high flow numbers". Most people want streetability and that requires velocity! High flow numbers have poor velocity at lower RPMs. When I was building HEMIs everybody wanted high flow numbers but it was the lower flow/higher velocity heads that people liked better. Unless you are building strictly a race motor that will never see less than 5000 RPM, stay with the smaller head. Heck - on a dyno pro-stock builders don't even start the pulls until 7000.