4g63 = NO
srt-4 = NO
Researching the situation further = YES
This "friend of the family" obviously doesn't know the extent of everything involved in order to perform a swap you seem to be wanting. For the money you're willing to spend on another engine to do this, you might as well just buy the parts to boost the 420a instead. Depending on how much this shop knows, and is actually planning on doing for you "labor free", you can easily attain this goal of yours...without the headaches and unforseen problems that would arise with said swaps.
I'm like radio shack....you've got questions, I've got answers haha
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-Xavier-