Too sleepy or too sober - one of the two.
Should work - the head ports didn't change (much) between the 0630 and 0331 heads, and the manifolds are, as I recall, swappable.
I'd suggest getting bronze or brass bolts while you've got it torn to bits (since those won't gall on the iron from heat,) and use brass allthread to make the end and centre studs.
Apply RTV copper to both sides of the gasket - THIN layer! - and use LocTite 272 to retain the bolts (nothing else works.)
While you're about it, make sure you have the little "dish" washers on all the bolts/nuts (if you don't, you can get them from MSC Direct or Small Parts, Inc. - they're called "Belleville Spring Washers," and the replacements will be a little thinner - they'll work,) and get some brass nuts for the collector studs down at the exhaust pipe(s) - they should be 3/8"-16.
Just a few helpful hints...
5-90