Elly Girl, That's what I did had to put trust in a shop here. Pulled out the 305 and dropped a 350 in my 1980 Caballero. Total cost having Marshall put it in cost just under $4,400.00 And I too have a Holly Carb. Also have headers on my car so I love the sound now with the new engine. Good Luck. Michael in SOuth Boston, Va.