OK, those numbers from the head look like they are from the passenger side - they don't help. The casting number that IDs the head is on the driver's side, forward of the carburetor, over one of the exhaust ports. Very easy to see and will be 7 digits long. First photo shows where to look (red arrow), and the second photo is an example of the head casting number (this one from a '54 235).
The J suffix in the engine serial number IDs the block as a later 235, a Thriftmaster engine for truck service, as you know. Would need the date code (raised cast letter/numbers from near the starter) to date the block more precisely. The third photo shows an example of the date code, and where it is on the 235s (red arrow). For this example, F decodes to June, 7 is the day of the month, and 4 decodes to 1954.
Hope this helps... a bit more to confirm the head specifics, but I should have said yesterday, it will probably work.
