How much would I lose?

How much would I lose going from a single plane, i.e. Holley Strip Dominator, to a dual plane, i.e. MP aluminum?

Especially if I have w2 heads? (both intakes are w2 lol)

Here is my combo:
--1970 340 block bored/stroked to 422 cid (JE pistons, Eagle H-beams, Scat forged crank. Zero deck ft with a slightly higher compression ht than off-the-shelf JE Pistons (still not sure how that works, but it is on my JE receipt that I got from the PO) main studs/girdle, sonic checked, etc etc. It will last a while.)
--Comp custom solid 250/254 at .050, .584/.568 lift, 275/288 adv, 104ls,
I don't have the heads in front of me yet, but here is what I know: 810E heads, will be ported by me. Maybe. Unless I can scrape up the money to send them out. 1.6 MP roller rockers. The heads are open chamber, dual bolt pattern. Have "Mopar" and "w2" cast into them. Flat rocker stands would make them the "race" head, as far as I can tell.
--as for headers, I will get the best I can afford...they will be at least 1 3/4. Carb, at least an 850 Holley. Yeah, I just sold the exact same stuff last December. Crap.

Anyway, I don't think this will be a super-high revving engine, as the cam is on the small side for that many cubes. I think the heads will flow great for the cam, could probably use a bigger cam, but its what I have. All in all, I think it sounds like a good combo...right?

Back to original question. How much power would I lose going to the MP W2 aluminum dual plane? The reason is this. I have this sick, disturbed image of painting the whole thing blue (like what was in my 73 Dart Sport 340), with the dual plane, stock type valve covers (I'm sure I'd have some re-working going on there), etc. Only the trained eye would see the differences from stock, otherwise it would look like an ordinary sb with big headers and a holley. But, I'd like to run deep into the 11's also.

What do you guys think?

I know a lot depends on the trans/converter/gears/etc. I'm saying if it was all set up right. Heck, give me some opinions on that too. Drivetrain is up in the air right now, I have so many options. I would love to have a 3.23 geared 11 second car, but I doubt that will happen. I may even go 4-speed. I dunno.