What is the best lt’s engine and transmission to swap into my 87 regal

[Malibu795]

Hi, I don’t want a 6.0. I’m thinking a 5.3 what would be best?

4.8/5.3 will be a nice improvement..
Even the 4.3 V6 LU3/LG3 or if you score a LV3/LV1 '14 and newer...

The LV3(w/AFM)/LV1(w/o AFM) are more E85 friendly than the older V6s
All run standard GM 90° V6/V8 bell housing pattern.. OEM trans was a 8L90 behind the newer V6s

In OEM trim... The newer 4.3 V6 makes roughly same HP/TQ as the 4.8/5.3 V8