The 292 crankpin is 2.100" (same as 1968-* SBC), the Ford is larger at 2.123".
The mean piston speed in f/m is entirely controlled by the stroke length: stroke × RPM ÷ 6. Piston acceleration varies slightly with the rod ratio.
Based on the 250 deck height of 9.15" and the 292's 4.12" stroke, a 5.40" rod makes the piston CD about 1.69" - which is fine for the piston but makes for a very bad rod ratio (1.31:1), and a high rod thrust angle: 22.4°.
Even with the V8 5.7" rod, the angle is 21.2°, very bad.
A 6" rod is better at 20.1°, but the piston is way too short at 1.09".
Best advice: just get a 292 motor.
Fast & cheap 250: Eaton M90 from eBay for $300.
