We see over .040" of lost lift at the valve from deflection even with a 60MM cam, individual steel rockers and single shafts(two bolts per rocker three per stand) with as big a pushrod as we can squeeze in it on the SBC in the Vette. Point is deflection is always there and the bigger core helps. Be great if we could get a 9 cam bearing block that also helps a ton. But only going to find that in a couple applications. We have planned to go to a clamshell bearing so we can go to a bigger lobe to gain the lift we think we need to compete in NA10.5 given the deflection losses we see. We simply cannot put a bigger lobe on the cam now and clear the 60MM bearing..Point is deflection is a real thing, the bigger the stick the ore of it you will encounter.

Are you asking me? Yes, all of my journals are 55MM roller bearing with an enlarged cam plug register also.

I think once you start getting near 0.500" of lobe lift, going up to a larger core is a must. If you are paying for a custom core, plus enlarging the tunnel, it wouldn't make sense to not go up to 60 mm. There is a conversion babbit bearing that allows the use of a 65 mm core in a roller 60 mm tunnel as well. Or go up again using clamshell bearings, which gets spendy.