1972 K20 towing capacity

[DJ_]

So problem is I have 1972 K20 with a 5.3/4l65/np241 but the previous owner took off the axles and put 1/2 ton axles and so you can call it a k10 lol . but I plan on putting back a 14 bolt and d60 in front. and putting 4.10s because right now I have 3.73s and I have a 5 inch lift on 35s. But my goals is to tow a 5k boat during the summer and a 7k-8k inclosed trailer during the winter and I want to know if after I swap the axles and put 4.10s will my truck do this comfortable? In the future i would love this truck to pull a 10k-12k tow hauler because that would just look great driving up to Glamis and Pismo beach. What would guys do to make a truck like my truck tow good?Like sway bars front and back, disc brakes all the way around? sorry for sounding like a newbie Im just new to this old truck thing lol