he Windsor used the 265 AFAIK through 1954.
All sidevalve engines ha the same disadvantages (vs. OHV): low maximum compression ratio and poor breathing.
They have 9 ports (235 has 7): 3 siamese intakes, 6 individual exhausts, which allow for a true tuned exhaust system and benefits from (relatively) high overlap.
All flatheads can be improved using the same methods: head mill, tight quench, deck the block, relieve the deck, offset gring the rod journal to increase stroke, bigger valves, regrind cam, bigger springs.
