350 or 5.7 wich to put in my truck?

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I have a 71 c10 that ive been driving for a year, the truck sat for about 10 years before I got it.
I converted it to an hei distributor and replaced the th350 with a 700r4 transmission. But the engine has uneven compression and kept fouling #2 and #8 sparkplugs and now looks like its getting water in the cylinders, so I its about time to rebuild it or replace it. The original 350 its pretty inexpensive to rebuild, I saw a kit on ebay with flattop pistons and an rv cam for arround $300. All the labor I'll be doing myself. So my question is if I'm going to put time and money into this, should i use the same engine or get a newer core engine with the centerbolt valvecovers. I plan to keep it carburated and use it as a daily driver. Any help or comments are greatly appreciated, thanks