Lottsa variations in that gasket over the years, back when several manufacturers made gaskets for the IH stuff each had their own type...some cork, some vegetable fiber (paper), some were composite materials. I have one fel-pro gasket set here for comparison, the distributor gasket in it is a rubber/cork composite.
I prefer to use an "o" ring, much nicer to deal with and can be re-used many times if need be. It'sa standard spec "o" ring, the dimensions are:
thickness (width) is 1/8", id is 1-3/8", od is 1-5/8". The as568a "standard reference" number for that item is:
2-220
do not use any sealant on that "o" ring!
The same "o" ring will work on any IH-app distributor, Holley, prestolite, or delco, the "lower" of those distributor are nearly identical except for the lubrication hole.
What's the spacing of the drive gear-to-housing on that fresh distributor??? Check it with a thickness gauge and record! That is the same spec as "endplay"...the tighter it is (within reason), the more accurate the timing throughout the rpm range. I'm now settin' 'em up as close to 0.016" as I can git 'em.
