[Freddo]

Hi everyone,
I did a tuneup on my truck about a year ago. (New plugs, wires, distributor cap, rotor, condenser, points, set timing according to the manual. I think 12 before tdc if I remember correctly.) My truck is a 1967 C10 with a 283 with an oversized Edelbrock 4 bbl carb & Turbo 400. Just an old farm truck. Odometer reads about 15,000 miles which I’m guessing is 115,000 miles. I’ve owned it for 10 years. Odometer was at 7,000 miles when I bought it, so I haven’t put a lot of miles during my ownership. Over most of the 10 years, the engine has ran smoothly and ran exceptionally well for a while after the tuneup.

Over the past few months, it has developed episodes of running very erratically: it misses, loses power and pops, sometimes very loudly. One pop was severe enough to blow a hole in a muffler that was just a few years old. (It has dual exhaust). It is very loud now. These episodes have been fairly random and usually, it would correct itself and run ok. (When it is behaving this way, it sputters and pops, and will barely go down the road. I usually pull over and wait for it to correct itself, and typically it has corrected itself after sputtering along for a while.) At one point, we pulled one plug wire at a time & #8 was not firing. We removed it, cleaned up the plug & it ran pretty good for a couple of errands.
It has gotten progressively worse again and When I pull the plug wires, one at a time, it doesn’t seem to make any difference. It is now running terribly and I can’t take it out of my driveway.
I thought I would try to change the plugs and maybe put in a slightly hotter plug. The plugs that are in the truck are the R45ts plugs and I tried to put in the R45S plugs which I read on this site were a little hotter and should fit. The R45s plugs have the wider base and won't fit into the head. (See picture)
Sorry for the long winded post, but I was hoping to give enough info so that you might be able to offer some suggestions.
Here are a couple of questions:
1. Is there a plug that might be one step hotter than the R45TS that I might try that fits this engine?
2. Any other suggestions that you can offer to get this thing running better?
Thanks in advance for any help or suggestions you can offer. I don't do a lot of posting but I am on here all the time reading everyone's posts and learning.