Height doesn't always mean you need longer clubs. If you can swing it, find a good fitter to help you out. I know that is not always an easy option, but it is the best route to go. Having been through a few fittings, I can tell you that adding even just a half inch can make a dramatic difference in control. Works for some, but not all.
As for measuring, lean the club against the wall at the lie angle, and measure directly in line with the shaft from the grip end to the floor.

As Barry said, height is not the only predictor. Wrist to floor distance is a better predictor. At 5’10 with short to average arms, my wrist to floor could be longer than yours.

Stock clubs are for an “average” player. Like me being 73, you being 6’5” is not average. Ideally you need to look for a Premier Titleist fitting site or a sponsored TT event where the will have multiple length fitting shafts and the fitter can work with your size and setup to determine if you need a different length. If you are serious about improving your game, it will be well worth the time to schedule a fitting to get it right. Any box store fitter can fit a 35 year old at 5’10” to 6’1”. The top fitters are the brain surgeons of fitting and you will have a better outcome than with a generalist that routinely fits the average size player.

The Fittings tab on this website can help you find one.

To measure the length of your clubs I would recommend buying a 48" ruler and lean it against the wall such that when you lay the club against it the club is properly soled . If the club is gripped the shaft length will be 1/8" to
1/4' shorter depending upon the grip cap depth.