I was thinking that 720cc primary/720cc secondary would be a bit much, because that's enough fuel for about 300rwhp, and I doubt I'll be near that number any time soon and the big primaries might make my car run like ****.

So I was wondering if I could use my (good condition) 460cc primaries with the 720cc secondaries. I only have an S-AFCII to control it.

 

Yes.

 

It won't stumble or anything when they kick in? The 460s should be fine for the low end, right?

 

That's yet to be seen, not many people with a wideband report back on their low end AF/Ratio. Anyway, it'll be fine, they're small enough where they can still be controlled pretty well, you may notice a rich spot, but it won't be a stumble.

 

Alright, cool. If my engine blows, I'll give it an agressive streetport, then maybe it'll need the 720s.

I'm also throwing in a Walbro 255, so I guess you're right, should be fine.