Hi Keith,
I saw Siggi's reply just after I sent mine.
He has a lot of experience with 2465 'scopes and always makes a lot of sense in what he says.
As an example, he may well be right re. transient response adjustment: After NVRAM replacement you don't need to do it, only after repair, exchanging parts or bending leads like those to the CRT. I don't know why you want to calibrate your 'scope, just assumed "full calibration".
Although horizontal (timing) employs verification by eye, you do need enough time resolution to be able to do that. A highest-resolution 2ns is used, right at the end of the Siglent's range of *sine wave* signals. The Siglent's square wave/pulse ranges end at 120/150MHz. Note 2465B SM 070-6863-01, Table 5-3, starting at point 28. Some adjustments only apply to some S/N ranges, see SM.
Vertical: I didn't check if your synthesised generators provide enough accuracy. The Siglent does provide enough resolution but I couldn't immediately find anything about its accuracy, except for DC.
The HP 8112A is analog, except for its controls. It is useless for anything that needs accuracy.
Raymond
Raymond Domp Frank