I love you guys....................Sorry, I couldnt resist.
Andy: Yeah, Im with you there. That would be the best possible situation. even if I needed to machine a small extension to grab the pilot bearing and the crank it would still be the easiest path. I have been operating under the assumption that the H55F input shaft would not be long enough. The only way to settle this is the measure all the parts and figure it out.
Rhino: I have 2 primary goals here. First, I want to make the 4bd1/2 a more or less drop in upgrade for 40-60 series lancruisers. If I use the existing adapter then i have to move the entire drive train, cut the driveshafts, fabricate or move crossmembers, etc, etc. The adapter is great for the GM trucks that it is meant for but its not what I am looking for.
Second, I want to make it affordable. There is no way that a custom bellhousing would be affordable for the average guy unless ordered in the 100s quantity. I think that the solution will retain either the stock isuzu or toyota bellhousing, possibly modified. I just realized that, if it will clear the firewall, the isuzu would be preferred becuase the amount of material required to fabricate the adapter would be much less on the tranny side than the motor side. On the motor side you end up trashing the entire inside of the ring. That could easily be a $50-$100 hunk of metal. I will look into the lakewood company though, never heard that name before.
You are probably correct about the flex plate flexing but i have never actaully held one to gauge its strength. I see that as the simplest of the problems to be addressed. The extra distance could be made up in other ways, such as creative starter mounting or lengthening its shaft.
I do have access to balancing equipment so no worries about that.
Keep the ideas coming guys. DRE(?) and Rhino, you are the guys actually biting the bullet and getting it done. I have a lot of respect for that. The whole cruiser community is going to benefit from the instights you guys are providing. With a little more work we can make this a modification that is as easy or easier than a SBC swap. Screw the oil barons, I'm going diesel.