D,if your a bit handy and you have a mig,there easy to make out of rectangular tube.You just have to make sure you weld in crush tubes inside where the centre bolt would sit and box both ends of the tube to stop any crushing,weld in a centre bolt and your away.
Mild steel tube comes in a host of sizes.Your U bolts will be the only issue if you make them too high.I have made several sets over the years without issue,and have also purchased the ones on ebay,which always need to be modified anyway, but you get nice long U bolts,i actually have an un opened set sitting on the shelf waiting for the next car i said i would never do again.

John have you actually had those fitted? They look like 1200 blocks to me, the size of the locators is different.
Like bert, I had to mod 1200 blocks to fit.
This is what I had measured up for a 1000...ended up turning a larger sleeve to fit the locator on top and boring out underneath some 1200 blocks:

nah never fitted them, don't really trust blocks to tell you the truth dont even know why i brought them lol