You think you are really going to crawl a truck that has that big of a motor in it? I've seen older regular pickups with Cat motors before and they were nothing more than street rigs. SWEET street rigs, but street rigs. You'd better have a strong intermediate shaft between that trans and 205, not to mention you may well find the limits of a 205. Consider the intermediate shaft will be put under whatever torque the motor produces times your first gear, say what 12:1? ouch...
not to mention axles. don't know what you are thinking but I'd bet a 60 would be crying for mercy under the weight and torque. Rockwells may work, and if you went that route you would have 6.72:1 axles so crawlability would go up. But then you have width issues vs the body.