The 18 head-bolts is one of the reasons for referring to this year's 235 as oddities.
The Powerglide 235 (used in most cars with hydraulic lifters but used in Corvettes with solid lifers) was the first high-pressure (full-pressure) 235 engine. It had 18 head bolts, as did all 54-63 235/261 engines. It also had only two valve-cover bolts, as did all earlier 2167/235 low-pressure engines.
Your block is a low-pressure oil-system block (as were all the earlier 216 and earlier 235 blocks), but your block has 18 head bolts, while all 216 and earlier 235 low-pressure blocks had 15 head bolts.
Thus, block/head casting numbers and engine ID serial numbers seem to be the best way to ID 1953 235 engines.
By the way, what is your head casting number and your engine's head block and head casting dates?
Here are some photos for locations that might work for a 1953 engine). If you looks for these codes, would you please post them and indicate if their locations are as shown in my photos? Thanks.
Someone else will know for sure the answer to your side motor-mounts question but I do not think that the side mounts with threaded bosses were found on truck 235/261 blocks until sometime in the 2nd half of the 1950's (I am almost certain that they were not cast into 1947 to 55-1st series Advance-Design trucks' blocks).
Tim
