new tranny or new gears??

[Facetime]

I have a 4 spd SM465 that I was hoping to replace with the NV4500. The reason for doing this was due to new 3/4 ton axles that were going in that have 4:10 gears. Wanted the OD to help with daily street pounding which is 90% of what this blazer does. The axles and NV4500 were to allow me to tow the boat the 15miles to the lake which I might occasionally do if the blazer were capable. (boat & trailer are 5000lbs dry) That project is creeping into the $1800-$2500 dollar price range depending on how good a transmission I can find.

I called my driveline guy and he said he can put 3:73 gears in the 14bolt GM that I am putting in for around $800. I have a set of 3:73 gears I can swap into the front axle to match.

My question...anyone know if the SM465 can handle that weight? As a daily driver the truck will have 33in BFGs, do you think the 3:73 gears should get me down the road at 60-65 around 2200RPM? Not great but better than the 4:10s with the same transmission. Thank you for your inputs!!
Cheers.