My guess would be a burnt-up TRB from too much bearing pre-load? That is unfortunate.
You can buy bulk gasket material in just about any auto parts store. I think it cost me less than $5 to get enough to make all my gaskets in several different thicknesses 1/16"(.062") 1/32" (.031") and 1/64"(.015). That and about an hour or two with a exacto knife and scisors cutting out the new gaskets. I traced outlines from the best surviving original gaskets or from the housings/coverplates directly onto the new gasket material. If I need a thinner shim, that material can be found also, but I find that manilla business envelopes are good for about .005"
The different thicknesses allowed me to mix and match for proper spacing of the TRB housings to achieve the proper shaft endplay when the bearing carriers are torqued in place. Mine came with about .090" worth of gaskets total under the TRB housings(2 under one housing and three under the other). I had to almost double this thickness to get the proper endplay(.005"-.008"). You will need a dial indicator and clamp bar to set this up properly. It is then just a matter of stacking gaskets under the housings to get the proper end play and of course make sure you don't cause any interferences inside such as the crank touching the idler gear. Like wheel bearings some can do it pretty good by feel, but I prefer having a number I can compare to at a later maintenance check. On the Utterpower website, under the kit engine review Quinn F goes into setting up the preload a little bit.
Mine was delivered so tight, I couldn't hardly roll the crankshaft by hand trying to twist the bare shaft. I had to put on the "V" belt pulley to turn it. It would have required additional gaskets even if I hadn't damaged so many of them during disassembly(painted in place). As soon as I loosened the nuts on one carrier, the crank that was setting near TDC rolled by itself to BDC under the force of gravity.
A 0-6" dial caliper and a 0-1" dial indicator and clamp bar are pretty handy for measuring dimensions, checking runout, endplay and finding other critical measurments such as TDC and valve opening/cam position. If you don't have these tools, some workable versions can be had for not much money at harbor freight tools.
As Doug said, you should be able to carefully knock out the old seal and get it matched fairly easilly at a bearing supply house. Or you can use the above mentioned dial caliper to measure the shaft(2"?) and measure the hole the seal is driven into(?") and take those numbers into the bearing supply house.
Good Luck
Ron