273/318 Offy Dual Four Barrel intake

I have this intake on my 340 ,and I raised the intake ports by welding extra alum to the top of all the runners . about 3/8 inch high and back 1 1/2inches then gasket matched them to a 340 intake gasket and went inside the runners and opened them up a little, it worked perfect and yes the bolt were tight . my manifold was new ,block was not decked . I used stainless header bolts for the mounting with 12 point heads. its the one showed in the pic (blue engine)also they sell 2 manifolds /I ordered mine for late style 273/318 heads holes were 3/8 inch with correct angle, they might just drill them out to fit. both have same casting # I port matched it to the 340 gasket but there wasn't enough room to hold the gasket ,it was thin around #1/3 so welded it up on all ports so I could shape the runners better.(the one pictured looks like mine with the late bolt pattern, with larger holes and bolt angle. (also with fit/alignment on the bolt holes being too tight I found if you use a steel intake gasket the manifold fit ,with felt-pro/ victor style about .060 /.040 it raised the manifold up making it hard to alien the bolts. I think they made the manifold to thick/too wide on the flange sides . so you can machine it about .020 on each side or just drill the mounting holes larger .)