One problem with putting a sbm where a sbc was is the Mopar starter location. The Mopar starter is on the already congested driver side of the engine, while the Chevy starter is on the much more open passenger side of the engine. Add to that how easy (and inexpensive) it is to buy things like headers and plug and play wiring harnesses for the Chevy over the Mopar and you beginning to see the problem. Then there is the need to change the transmission or buy an adapter to connect a newly swapped in Mopar small block to the remaining Chevy drive train. There are also a host of small issues, but additional issues just the same.

Nothing impossible to overcome, but an added expense and work load compared to jumping in and driving a rod. Now, if we are talking about an unfinished build, it may or may not be a different story.

For me, I'd have to want the Chevy drive train car bad to go for it, I would rather start from scratch then re engineer a car. Gene