Have you narrowed down the type of 235 you have? The 1953 standard transmission 235 engines still had the low-pressure oil system, babbitt rod bearings, cast iron pistons, external oil distributor, etc. The 1953 Powerglide and all 1954 engines would be the best fit, as they have the full-pressure oil system. aluminum pistons, and the high, short water pump like your 53 3100. The 1955 engines (except for the first series pickup trucks) have the low, long water pump that usually requires modification to fit in a pre-55-second series truck. There are adapters or modified water pumps available, however.
As Drew mentions, the front mounting plate from a 54-55 engine may need to be drilled to accept the 1953 truck front engine mount, and any full pressure 235 would be a great replacement for a 216, unless you are trying for a stock restoration.
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