[franken]

Go to advance adapters web site and get their GM conversion guide as a pdf. It'll tell you more than you need to know. Also, search this site. There are a few threads about users doing the same swap. I think Dirty Larry did a long writeup on a swap into a square.

I think the 205 needs to be machined for a larger input bearing and a new 32 spline _short_ female input shaft installed. The shaft is ~$150. Or snag a round pattern 32 spline input 205--they aren't too common. Around 1985 GM started making 1 tons with SM465, using a 32 spline round pattern 205, but if I recall they used a long input. The short 32 spline input was used on earlier TH400 trucks. A spacer is available to use the long input to mate a long input TC to the 4500. I have one I don't need if you want it for half price.

You need a round pattern (4500) to figure 8 (205) adapter (AA, NW fab, etc.) if you stick with your TC.

I don't think that trans will bolt to your bellhousing so there's another issue. Some have reworked the existing BH, and others have used the 4500 BH. Some or all 4500 BHs have the opening for the hydraulic lines or release arm on the passenger side. A new BH from AA is ~$350.

Then there's the hydraulic clutch release issue. Yours is/was mechanical when stock.

I measured the 4x4 4500 in the garage and its 20.5" long. I'm guessing that's longer than an SM465. You'd measure the 465 and the TC adaptor since no adaptor is used on the 4500--it bolts to the TC.
If the trans is longer, you're looking at shortening and lengthening driveshafts.

The TC shifter needs a new mount. I can snap some pics of the one I have if you want. I think it puts the shifter in the stock location, but mine came from a squarebody. You might check AA to see if its the same for 67-72.
The 4500 uses special lube that's expensive to keep the synchros alive and when people use the wrong lube it wipes them. Then there's the 5th gear falling off issue...

Dodge and GM 4500s are somewhat different, but I've only had GM so I never paid much attention. GMs can be divided into ~93-94, 95, and 96 up. The first group had a different front bolt pattern, 6.x:1 1st, and no sybchro on reverse. 95 shared a few features of the early and late versions. 96 and up used the Dodge front bolt pattern, a 5.6:1 1st, synchro on reverse. You may want to fact check this since its been a while.

That's all I can think of right now.

I have a 96 4500, doubler, and round pattern 205 in the garage waiting to be installed so I've done a lot of reading on the subject, as well as trolling scrapyards, buying/selling/trading parts for the swap, etc.