That thread has been very helpful, and has been a major inspriation to me to start my own project!
Problem is, my bus is a '71 with the type 1 style tin arrangement. This leaves a smaller hole for the engine unless I want to cut. I would really like to leave the option open to return to stock, but I might end up cutting out a single piece of tin that could be reattached later on if desired.
I was leaning toward the EJ25E single cam engine, as these are becoming more available hereabouts, but haven't been able to find any dimensions. The EJ22 is also a viable choice, but those extra 25 horsepower are oh so seductive.
I've also looked at a Ghia conversion on this site and it seems as though he managed to squeeze the EJ22 into the stock type 1 engine space, at least in the front where the bus tin is fixed in place. I've heard conflicting data as to whether the EJ25E has the same dimensions as the EJ22 and figured that this forum would be a good place to get a definitive answer.
Another concern of mine is whether the EJ25 is at its displacement limit for its basic design, making the EJ22 a longer lived choice for bus service.
Thanks also to Jörg for the EJ22 dimensions. That one seems a definite good fit.
George