I am going to tell you to not waste your money on a girdle, the stock RB blocks fatal main weakness is the webbing between the bottom of the cylinders and the main bosses, take a hard look their to see what I'm concerned over.
All the stock 400 blocks are a lot thicker between the bottom cylinder walls and the main webbing up None of the other B or RB blocks have the thicker main webbing in them like all the 400 do whiney scope
My message is if you want to build a strong stock block race motor or any other pump gas motor with 600+ HP start with a good 400 block that is sonic tested first and then go from there twocents
I have seen 3 440 blocks and one 426 M.W. block that had cracks in the main webbing between the #1 and #3 cylinder going between the bottom of the cylinders and the main bolt bosses whiney
On the 400 blocks that I am going to build that sonic test well that will exceed 600+ HP I do replace the stock main caps with billet aluminum caps and ARP main studs up
Above 850 HP buy a new race block up
IHTHs thumbs

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)