No such thing as a Polara 500 in Canada in 1965-66. Series were 330 (1965) / Polara (1966), Polara 440, Polara 880 and Monaco. Standard engine in them all was either a slant six or a 318 V8 as the Canadian Dodge was priced to do battle with the Plymouth Fury, full-size Ford, full-size Chevrolet, Meteor and Canadian Pontiac. Being a 1965 there should be a small tag on the firewall with Model No, Body No, Trim Code and Paint Code. As yours is a 1965 2 door with bucket seats, it leads me to believe it is a Monaco. Will need to Model No and Trim Code to confirm.
If you cannot find the body tag the serial number / VIN will help. Advise what the SN / VIN is, minus the last 6 digits if you wish, and I can tell you what you have.
There was a red 1966 Canadian Dodge at the Langley show a couple of years ago. Couldn't track the owner down, but he said it was a Polara 500 although it had Monaco side trim..
American C body Dodges came with a 383 V8 in 1965-67, with the Polara models getting the 318 for 1968. The U.S. Dodge Polaras (D2-L) did battle with the Pontiac Catalina while the Monaco (D2-H) went up against the Pontiac Executive, Olds 88 and Mercury Park Lane. (The Canadian sixes were D1, with the 1965-66 V8s D2 and starting in 1967 D3).
For your exhaust manifold, get a 1967 or newer unit. The 1960-66 exhaust manifolds are noted for cracking. Starting in 1967 Chrysler used more webbing in the manifold to prevent distortion.