If you go with the stock 4-speed tranny and transfer then get the Mark's of Australia kit. It's a second bellhousing that fits between the existing bellhousing and the smallblock. It spaces the engine forward and leaves the tranny/transfer in their stock positions. Uses an AA motor mount setup. If this is a first conversion it's pretty simple. I'd recommend a heavier clutch and I can get you the part numbers for that.
Having said that, you are not going to get super low crawl ratios out of this with the stock gearing, even with 4.10 gears. Yeah, you'll have power and torque, but that's only part of the equation. This is a good, all around setup for a rig for hunting, vacationing, exploring, etc. It is NOT a serious rockcrawling setup. It needs either a gear swap, which will affect highway use and mileage, or it needs a reduction box. I'm not knocking this conversion - it's good. But, like all conversions, they always involve a compromise.
That's why you see the recommendations for a 465. Much more low range. Even around town the stock 4-speed with 33" tires is a pain in heavy traffic. I'm tempted to cut the block preventing 2High engagment just to prevent constant in-out clutching at 2mph.