Well as i see it, youve got two options.
1) A take out engine from an Explorer/mountaineer. it's 85lbs lighter than the iron block, which is great for weight distribution and handling. Its an equal to the stock GT block in terms of rods/pistons/crank, so it should be okay for less than 400 rwhp. Take out, drop in, done.
If that doesnt work, I'd choose:
A) any iron block PI engine (same as your current setup)
B) an NPI engine for a head swap of your current heads on to. (more work, slightly better power/efficiency)
C) an NPI engine as a drop in. (same as A but less power).
2) Building a cheap forged bottom end. This is very dependent on if you can get the parts and work done at a reasonable price, and reliably so. Unless you have done it before, it may be a little daunting.
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