Well, as a final report, I had to move the engine forward because of the HEI Distributor being so close to the firewall; then I had the welding shop make a 3/4" thick plate which was welded over the transmission mounting surface (that raised the rear of the transmission); then I found, with the whole thing forward abit, I now have about 1/4" clearance from the bellhousing. I'll follow your suggestions and trim about 1/2" total. I did think there was a possibility of noise in the cab with the floorboard touching the transmission and you guys reconfirmed that. I'm installing a lot of sound deadening material in the cab prior to upholstery so what happens here is important. Again, thanks.
