Keep in mind I've never tried this combo, but I think the the tri-power intake has ports somewhat like a low riser head. The ports in the intake may be lower than the ports in the ebrock head. This would be a bad situation. You want the ports in the intake to be same size or smaller than the ports in the head, not vice-versa.
You certainly would not want to lower the port floor in the head to match the intake as that would hurt flow and power. You could raise the port in the intake to match the head. That would likely help flow and power, but that is problematic also. If you weld aluminum into the intake floor you might distort the intake from the heat. If you expoxy in the floor of the intake you have to wonder how long it will be before the expxoy flakes off and goes into the head.
With some measuring and some calls to Edelbrock you could find out if this will be a problem for sure.
The alternate solution is to work on the heads you have. Pocket porting is the best bang for the buck. It will give increased flow and power with no downside. Enlarging the ports themselves can be helpful too. However, more care must be taken to make sure the ports are not made too big or you will lose velocity and low lift flow. Bigger valves are also a win-win in my opinion. You should be able to put in 2.09" intake valves and 1.66" exhaust valves as long as the cylinder bore is not stock 390 size (4.05") and maybe even then.
Cylinder heads make the engine so I'd spend money there regardless if you go with the factory heads or the Edelbrock heads.
Paul
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