There is no ideal setup for your engine trans combo. Most conversions would use a later engine which has the mount bosses cast into the block. That is what the aftermarket is geared towards. This would be a tubular front cross member with the center engine mounts and another tubular cross member for the rear transmission mount. These are available from numerous aftermarket suppliers. However, since your engine does not have the mount bosses cast into the block you would be unable to change the front mounts. The only option I can see is to fabricate some center mounts located on the bell housing to the frame as previously mentioned.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine