dollar for dollar the best mod I ever did to my 84 was put in the bigger engine.
I went through the header cam exaust rebuilt engine re gearing thing with the four cyl and could have saved myself a lot of headaches if I had just went to the bigger engine first
I went with a 4.1 buick engine since it was what I had available
it cost me 750.00 for the adapter and flywheel
300.00 for the engine rebuild kit
125.00 for the radiator
and about 200 for the engine mounts and adapters for all my accessories
a/c, air pump, alt, p/s, and what not
the headers were 200.00
and the exaust cost around 400.00
I ran 4.88's in it for years hated them on the hyway they revved it bad
with the 4cyl but it pulled a trailer ok but with the v6 it pulls on really good now
I ran 4:10's for a year or so with the 4 cyl and it did ok except on the hills and stuff and hauling was not good since you have to ride the clutch so much
that was the reason I regeared. because I hauled a lot with the 4cyl. and I had put three clutches in it in a year and a half or so
On the highway it sucked. Around town gas mileage was around 13 mpg on the highway it was worse or about the same but I was usually hauling a trailer.
I went to a bigger engine it took about 2 weeks to install it taking my time
getting the radiator modded and then the exaust put on. the wiring was easy
installing the engine mounts was as simple as bolting on pcs
my only issues with this whole project was the alternator hitting the frame in the new location. was a simple fix with a shorter belt. if I could have found a r151f turbo transmission and transfer case. it would have saved me some of the adapter costs and got me a lower first gear but I went to a r150f transmission from a v6 just for availabilities sake. I like a stick shift. but you can go automatic as well
now with 35x15.5x15 tsl's, 4:56 gears, v6, 23 spline stock gear crawl boxes, it runs great on the street and the high way and around town and I still get around 13-14 mpg. but the most fun is when I get to wheel it the extra power is just a whole lot more fun and the crawl box gives me all the gear I need.
After spending thousands on the 4cyl and never being happy with it's power. cam header, exaust, gears, engine rebuild, and was still not satified with the power and when I checked into the cost of a lc engineering block and the head and the other power increasing mods the hp range was to be about 160 - 200 in a highly modified gas hog of a little engine with no more available unless i spent a whole lot more.
and with the cost of the new v6 engine, adapters, radiator, headers and, etc. I was in a cheaper price range with the v6 and and would get about the same hp from a stock engine. If I wanted I could build the v6 even stronger.
With the mods I've made, it's in the 180 to 200 area and if I want I can get still more out of it.
I would never go back to a 4cyl
not with the way I use my truck.
some highway, some around town, lots of hauling, and lots of wheeling.
on the highway I can run fifth gear no problem
around town I can have fun if I want
and on the trails I got all the power and all the gearing I ever need
my only complaint is the carbed engine I'll eventually go to a efi set up
my recommendations for a built toy goes like this
tbi or tpi vortech v6
th350 transmission/ adapter/ 23 spline crawl box, or r151f turbo tranny and t-case/ 23 spline crawlbox or
you'll have a lot of other choices for tranny t case set up as well
sas with minimal lift 3-5"
trimmed fenders
crawlbox & adapters
beefier axles of your choice D44 or D60
you'll have more power than you'll need to haul or tow and
the strength you'll need to put what ever sized tires on it you want
and to with stand any type of wheeling you want to throw at it
It is going in mon. so we will see how it does.