Moss heavy duty motor mounts

Has anyone used the Moss heavy duty round mounts? Im just about ready to intall my motor and noticed that the mounts have only one stud and its 3/8 ". I dont want to drill out my metal bracket and screw it up for the standard mount. I have to get this thing together and running by tomorrow or else I will miss a great opportunity.
Its been a real stress test removing the motor Tuesday, getting all the machining done and parts together, prepping and painting the engine compartment, and fixing all the new parts that dont quite fit! Hope your having an relaxing weekend.

Rich Hagon

PS I know I should have just bought the standard mount but the guy said do you want "Heavy Duty?" " Of course! "

The round mounts are for the rubber bumper models ('75 and later). Looking at your signature you seem to have a '71 chrome bumper GT (nice choice by the way).

Thanks David, I guess Ill have to wait till tomorrow when Moss opens. I was hoping to get it on a dyno before taking it to Moss, but that probably wont happen.