An excellent choice for our truck! I have done this swap into my 51 Panel.

Through trial and error I came up with a mod to tubular engine mount from Trans-Dapt. I ended up using one for a 460 Ford. These tubular mounts are adjustable at the ends. I had to cut a little off the box shaped mount on the tube to allow the stock Buick engine mounts to go in squarely. I loosely attached the tubular to the engine and started to lower into the frame. Other than a about a 3/8" relief in the frame on the passenger side (using stock exhaust manifolds) the motor sits nice and low in the chassis.
You can fab up mounts of your own design, but this is how I did it.
With the distributor up front you can really push it back to the firewall. I did, and still had room for a column shifter (which I prefer).
I'm guessing your frame is similar in dimension; if anything a tad wider. The only other mod was to install an oil filter relocation kit; to avoid cutting into the forward frame crossmember.
If you want more details PM me & I'll be happy to explain further.