Don't sell your 350.. I would find out more specifics on that motor if your looking to increase horsepower. Seems everyone with a 400ci has 400 horsepower.
No plans to sell the 350 at the moment, but The cost to up Hp is excessive, and it needs compression boosted making it run hot and need high octane gas. , forged parts, etc. i just want a torquey street motor. How far will the 500 bucks for the complete 400 take me on the 350?
1968 Firebird, 350 4V, TH350 with trans-go, 69 slap shifter, 8.5 inch 10 bolt 3.42 posi