Should I go Big block or Small block?

I would go with the 440. The weight issue is cold be less with aluminum heads and intake. .

331/354 Hemi with alum. intake and water pump -504
392 Hemi with alum. intake and water pump ------ 564
Slant 6 ---------------------------------------------525
273-340 ------------------------------------------- 525
360------------------------------------------------- 550
361-400 ------------------------------------------- 620
413-440 ------------------------------------------- 670
426 Street Hemi -----------------------------------765