Here’s an example of how the $1675 for the manifold porting could be used in a different way.

You think the current heads are “too big”?

You can buy some std port stage 7’s(which is just a Victor head) from Mancini for $1300/pair with valves.
You can reuse all your current hardware and rockers. Headers will fit.
Sell your current heads and valves to finance some prep and porting....... and still have some left over.

Then you’d have std port heads, and that M1(or TF, or Victor) would fit just fine.