If you purchase a GM NV4500, it will fit your stock clutch and pilot bushing.
The internal shift linkages are significantly different, and the rear of the NV4500 case will not even remotely come close to fitting the SM465 housing. The similarities exist because the NV4500 was designed and intended to replace the SM465 when the GMT-400 3/4 ton trucks came out in 1993.
Advance Adapters 712577 (1992-1995) or 712576 (1996-2003) bellhousing mounts the GM NV4500 to a small block or 6.2/6.5 detroit diesel with a standard mechanical clutch linkage. They run about $400.
In order to do this swap you need to switch to a block mounted starter and change driveshaft length as noted.
This image shows the adapter bolted up with the new clutch fork just prior to installation in the truck. I retained my stock clutch and linkage. This is a 1995 GM 4wd unit, note the bolt on shift tower.
There are 4 different NV4500 variants:
'93+ Dodge - 5.61 first gear, 7.625" x 1-1/8" input shaft, .750" pilot diameter
Dodge HD (diesel) - 5.61 first gear, 7.625" x 1-1/4" input shaft, .750" pilot diameter
'93-'94 GM - 6.34 first fear, 6.625" x 1-1/8" input shaft, .590" pilot diameter
'95+ GM - 5.61 first fear, 6.625" x 1-1/8" input shaft, .590" pilot diameter
All of them have a 10 spline input shaft. The top cover for '93 and '94 has a cast-in shift tower, after '95 the shift tower is a bolt on unit.
GM cases '93 - '95 have a GM specific bolt pattern, GM cases '96+ share the same pattern as Dodge.
By far the simplest way to do this swap is a GM box with the AA bellhousing; this uses a standard throwout bearing, pilot bushing and clutch fork. If you are okay with a hydraulic clutch you can use the GM bellhousing from the donor truck. The Dodge versions use different throwout bearings.
If you shop around a bit you can pick up an NV4500 for less than $700 in good shape. High Impact Gear and others will sell you a professionally rebuilt GM box with whichever first gear you want and all the latest updates for around $2k
You will also find that unless you're wheeling or doing HEAVY towing, the 5.61 first gear is a lot more useful. Your SM465 has a 6.55 first gear.