I have a RCLB '91 F150 XLT with a 302 and E4OD trans (2wd). Main purposes for this truck are for it to be a DD 3-4 days a week and to do occasional hauling/towing of my ~3,000lb Mustang on an open trailer. The truck has done okay with the 302 and 3.55 gears, but it's far from optimal. I have considered swapping the rear gears for 4.10s and calling it a day, but with the amount of leaks this engine appears to have, it needs to come out anyway to be freshened up. Aside from that, the 302 runs like a champ and will cruise at 75 all day without issue. With that being said, I still purchased a 351W, non roller motor to replace it.
Not being satisfied with the output of a stock 351, I have also purchased a Crane 444232 cam/lifter kit, GT40P heads, longtube headers, a Typhoon lower intake manifold, and a set of 4.10 gears. I need to put some attention towards the E4OD now, and this is where I need some assistance. I have no idea how old it is or how many miles it has on it, but it works as well as I could expect from a 25 year old truck. And I'd like to keep it that way. While the motor is out, I figure it's best to replace the torque converter, but would a stock replacement be advisable with the added power and towing requirements? At some point in my truck's life, an external cooler was added which I'm sure has helped. Would it be beneficial to add a second cooler in line? Are there any other trans modifications that would help in the long run?

 

That trans needs a shift kit, and a temp gauge to keep an eye on things wouldn't be a terrible idea.
What upper are you planning to use with the Typhoon lower? The stock upper won't bolt on it...