Notched holes in intake manifold.

[Priesty]

Hi guys,
I recently purchased a dual plane manifold to replace my existing 340 Torker single plane. After removing original I noticed the bolt holes have all been notched out to an oval shape at the bottom. I also note a slight step under the front & rear gasket surfaces. Trial fit on my new manifold (without gaskets) has it sitting about 3/16" higher than the bolt holes. I assume this means the cyl. heads have been shaved by previous owner. Question is how much & what do I do to make new manifold fit? If I have the front & rear surfaces machined on the new manifold do the intake surfaces also have to be shaved a proportional amount & how is that calculated? What would be a likely amount that the heads would normally be shaved?
Starting to wish I'd left it alone. 
Appreciate any input.

[Brads70]

Bummer, either mill the intake to fit or remove the heads and finish machining the intake side to match what was taken off the deck surface. Makes one wonder how the ports line up? Or if they line up?
Any idea how much was taken off the deck surface? Either head or block? Or both?

If its just the ends holding it up that's pretty easy to fix. Might have to mess with different thickness of intake gaskets to get it sitting right? ( after you clear the ends)
After you get it machined check the port line up by running a strip of masking take across both the intake and head ports , then using shims to simulate gasket thickness , lay it on top and see how the masking tape lines up with each other. You might need to do some gasket matching on either the head or intake? If forced to choose/compromise you would rather have the head port bigger than the intake port , hurts airflow other wise. 

[Priesty]

Thanks Brad, I like your idea with the tape.
Unfortunately have no idea how much was taken or from where as it was done by a previous owner. I will approach a local engine machine shop next week & see if they have any suggestions. See attached pic, seems to be about a hacksaw width (.0025") off the bottom on all 4 corners, not sure if a corresponding amount has been milled off the intake faces.
Won't be pulling the heads so no porting to be done on them, but may tackle the manifold once it's adjusted to fit.