After you have bought a flange, got the donor manifold, paid the welder? For a (probably) inferior product how much difference can it be....and I bet I know where the possible failure item could be on the welded jobbie. Especially if your exhaust down pipe doesn't end up in the right place.
You pays your money and takes your choice....only another option.
Jays car has had some proper cash chucked at it, why skimp on the last bits?