273/318 take different mounts then 340/360. If you have a set off a 340/360 LA motor then you're good, as all Magnums take that style. If you have 273/318, you'll need new mounts.
If you look at the Schumacher site for slant 6 to small block V8 conversion mounts, they list one for the 273/318 and a different one for 340/360.
thats correct, we have them on the shelf and can probably make a special deal for FABO on those but you would have to call and talk to J, he does all the pricing and web stuff. magnummopar.