GR, when it runs, come drive it, or I'll bring it down to you or a rally.
Will, thanks for the point on the ring gear possibly being on the torque converter. I never considered that, even though having seen it before. A few eBay Allison 3000 MH transmissions seem to have this exact configuration, so I assume mine does also. I already purchased a "cup" type SAE #2 14" flywheel with ring gear for when I mate this ISL to a 13 speed Road Ranger trans. It should put the ring gear at the same location, and of course I have access to starters. I will swap over my 6CTA8.3 flywheel housing and starter onto the ISL to insure the rear mounts are at the same stock location and fit. For the test start I will leave the Allison trans as you said, and get a short jumper hose made at lunch today to loop the cooler ports on it.
I know I have said this before, but I hope to conduct the first test start tonight after work. We're getting close. I'm not going to scan for fault codes yet unless the engine does not start. As long as it starts and runs seemingly properly, we'll do a full de-bug once installed into the vehicle. As it sits on the trailer currently, there will be several fault codes such as accelerator circuits open, etc... Engine seller also asked just yesterday if I cranked it up yet, so I would hope to work something out with him if there is a major issue with the engine. Fingers crossed.