I saw this with the Pontiac SD four bangers used for racing. A company in Kansas made blocks that were beefed up factory design, but offered them with SB Chevy or stock head bolt patterns. The problem with swapping heads is getting bolts to align - either by changing the head or changing the block and (according to the Pontiac I saw) the block was easier. I think this makes sense because the head has the ports/valves/etc to work around where the block under the deck is mostly just open around the cylinders. On your layout, can you see what would happen if you wanted to drill and tap the block to accept the head pattern? There are companys that will weld the old holes shut so they are like original castings. You probably already thought of this, but it seems like few people know that GM and now Kansas Racing Products did a swap that is nearly what you are talking about. That four banger is very much like the 230-292 and even shares some parts.
