Low cost upgrades for 72 240

I'm looking for low cost, minor mods / upgrades for my truck. It is a 72 F100 short bed 4x4 with a 240, NP435, Dana 21, 4.10 gears (I'm fairly sure), and 31" tires. I'm running an MSD6 with a Super Coil, and the timing is bumped up to about 12 deg BTC, IIRC.
I'm primarily interested in a little bit of horsepower gain, fuel economy gain, and reliability. Torque seems to be adequate for me. I very rarely really work the truck, it is just something I enjoy driving, mostly around town, in the summer.
Until last spring, when I rebuilt the carburetor, I thought the 240 was just an anemic engine, and I wanted to do a swap. The carb rebuild made a surprising difference. I had been getting 12 mpg consistently, driving around town, I got a bit of increase in mpg after the carb rebuild, but mostly I saw performance increase. I now think that the 240 is something I can live with.
The engine seems to be healthy, less than 100k miles on it, and compressions are good.
I've researched on the internet, and at this point my thoughts are that upgrading the ignition might help with fuel economy, and maybe a little bit with horsepower, and that a split exhaust from a later 300 would help with horsepower.
My distributor is probably original, and I have doubts about the advance working as it should. I had been considering a DSII, but today I saw a post about adding a TFI to a stock distributor, and I thought that with the MSD and a new original type distributor might be a good option. With my gearing, I run at higher rpm's a good bit of the time, and my understanding is that MSD is much more beneficial at lower rpm's.
I mostly want a little more horsepower for climbing a hill on the way home. Right now I lose about 10 miles per hour climbing the grade, starting at about 55 and giving it all she's got in 4th gear. Last fall I hauled my tool box (850 lbs) to Anchorage (350 miles), I was impressed at how well the truck did with the extra weight, even climbing hills. I think it was on the way back, running empty, I got 17 mpg.
I've considered axle swaps and a tranny & t-case swap, but realistically, that's probably never going to happen. At least for now, I'm just looking for low cost and simple upgrades to try to eke out a little more horsepower and fuel economy.
Any input would be appreciated.
Here is an excellent rundown on 240 improvements.