Well Yos and Mike, we do have a member that could have answered that problem but he's not been active on here in just over a year.
His user name is hondarc174 and the company he worked for replicated six RC174s copied from what was believed to be the last one made by Honda and was never raced.
The big Honda Blackbirds were built the same way with the block being part of the upper crankcase.
OK, the Blackbird was only a four banger and the crank throws would have been staggered differently but it must be doable.