you might consider a saddle type mount. Speedway Motors makes frame mounts that are specific to 35-40' fords Part# 135-3312, then you will need a sbc saddle part# 135-6023 and a cushion kit #720-9314

You will still be required to pre-fit the engine to know where to place the mounts. Make sure that your motor has about a 4-6deg angle (nose up) when fitting it in the frame.... Makes the oil drain back toward the pump.

If you don't want to use the saddle mounts you can use something like #916-18002 and move the frame mounts back a bit farther. Moroso also makes mounts similar to these except out of steel and they are less beefy and cheaper. about $20 available through jegs.

www.speedwaymotors.com