Edelbrock Pro Flo 4 EFI

I'm looking to install this on my la 318, it says I have to use 340 heads?
My Dart is a street cruiser.
Can I get away with larger valves on my 318 heads ?
If not it seems like a lot of work to use 340 heads as the setup between a 318 and 340 is a lot different.
They say the kit is for 318-360 but I dont know how the big intake ports would work with the small 318 heads.