Think he said 3.55 above.
"59" is probably the year of the camper not the length haha back then the shasta's were most below 20' long.
The cam he is talking about sounds like the specs of my Oregon cam which is the 819. Specs around familiar although I'm not looking at my sheet at the moment.
235/85-16 is about a 32" tall tire.
The mentality has been "dump the 6, put an 8 in" for years.
This site is full of people who prove the "dump the 6" mentality wrong ......I'm doing 2 trucks. One is keeping a /6 albeit a little hopped up the other one is a heavier 3/4 ton that's keeping it's v8.

With those tires I would change the Rear axle ratio to a 4.10 or maybe a 3.91.


Okay. I thought it was 59' as he typed..
A '59 less than 20' will be fine.

I would still like to know the weights of those trailers.
Towing on flat lands or in the mountains?

I'd rethink that Aussiespeed intake. Not really well matched to the vehicle and intended usage, and super-not-cost-effective. You'd be better served by a stock-shaped, heated 2bbl intake, whether that be a factory 2bbl item, an Offenhauser 4bbl intake with a carb adapter plate on it, or a 1bbl intake modified to suit a parallel 2bbl setup (photo documentation of a very well done such conversion is here, and there's a nice pictorial on modifying a 1bbl intake here).

Dutra Duals are a fine idea, configured as originally conceived (rear half of a cut/capped stock exhaust manifold + new front-half casting—not two new castings). Exhaust system recipe: 2" pipe off each of the manifolds, join those two 2" pipes into one 2.5" pipe with this collector, and run 2-1/4" pipe into this late-model Hemi Ram muffler (big, free-flowing, quiet, stainless steel). Appropriate tailpipe dumping out at the rear corner of the truck, spout angled outward between 30° and 90° and downward between 30° and 45°.

Ignition: HEI.

Charging system upgrades like this. Alternator upgrade's a good idea. No need to waste money, time, or brainpower on exotic ones; just fetch a stock alternator for an '89 D-150 pickup with 5.2 or 5.9 engine. This one if you want 90 amp, or this one if you want 120 amp. They both come with a suitable 2-groove V-belt pulley. Minor bracket modifications will accommodate it, and it won't even look all that different to original, just smaller.

Regulator: Mopar-type external; this heavy-duty adjustable one.

Upgrades to the brakes, seatbelts, headlamps, etc are a very good idea to go with the high-zoot motor. Shop carefully; there's a ton of fraudulent/bad-idea junk on the market, especially in lighting. General idea in this post.

where are you located?

Given i've already got the the intake & dutras installed - do you still recommend pivoting to something else? I plan on putting in some sort of heater/plenum box below the intake to alleviate the heat issue.

The mismatch here is an intake designed for a high-RPM motor (more detail on this if you want it) and an application (truck) calling for a low-RPM torquer motor.

An add-on heater (waterbox or whatever) can slowly and inefficiently bring not enough heat to the intake, but won't resolve the mismatch. Undoing the manifold install to put in an intake that will serve you better would be the smaller nuisance in the bigger context.

You got a great deal on those items. It's easy to get carried away buying high-zoot parts. Fortunately, that also means it's easy to sell them!

(A Holley 350 isn't a terrible choice of carburetor. Not the one I'd pick, but that's a different question.)