Varget is my go to powder, but I am running low and found a 8lb jug  of IMR 4064 at PSA for $112.

The only manual I have or know of that has M1 specific loads is the Hornady. They list 4064 in the 168 gr bullets, but not in the 150.
What would be a safe range to load using this powder on the 150 gr bullets in my M1.

I also have some Win 748 and 760 with no M1 data for the 150gr bullet.

Certainly would appreciate your input

IMR 4064 is my favorite powder for use in my Garand.

49.0 grs with a Sierra 150 gr flat base softpoint gets me 2750 pfs and is just above a starting point using an older Hornady manual. Research a little more rather than accepting what some faceless stranger on the internet said, but 4064 is certainly a good powder for the Garand.

I use a lot of IMR-4064 for a Garand. With a 150 grain bullet 49/5 to 50.0 grains is about max but my load is 49.0 grains and works great.

With a 168 grain bullet 48.0 grains is near max but my most accurate load is 47.5 grains.

With a 175 grain bullet 47.0 grains is near max and is my load.

I like Varget for the Garand also.

Note the Hornady A-max bullets are a but longer and have a lot of bearing compared to most others and the Hornady load data max may not even be max but where they stopped with certain powders for various reasons.

To compare here are my Varget Garand loads.

With a 150 grain bullet I use 48.0 grains of Varget.

With a 168 grain bullet I use 47.0 grains of Varget.

U don't load the 175 grain bullet using Varget.

Avoid current Winchester primers, despite what Hornady recommends. Winchester has a new plant and many problems.

With the 150 gr FMJBT style bullet you should find 49 grains of IMR 4064 accurate in both the Garand and the M1903 if you have one.  A really good combination.

You can also use W748 in the Garand, but not W760 as its a bit too slow and high volume for the gas system.

W-748 can work, and should only be used. It requires a hot magnum primer, especially in 30-06. The NRA max load with a 150 grain bullet is 49.0 grains. Winchester once published service rifle load data when surplus were first allowed to be imported again. Winchester had just switched to transducer PSI pressure measurement from copper crusher CUP and the their first results were a bit mild. Winchester published a load of 48.0 grains of W-748, which isn't a terrible load but don't load lighter with a 150 grain bullet as the case fill won't be enough. The absolute max load for the Garand is 50.0 grains but it is slightly hotter than most military ammunition. Not by a lot but the NRA load of 49.0 looks decent. Maybe start with 48.0 grains as some people complain that the burning rate of W-748 varies more now, after Hodgdon took over distribution  of Winchester powders.

1st of all, any standard 30-06 load in any manual using IMR 4064 will be safe in the Garand.  (standard "work your load up" warnings apply)
As long as you are using IMR 4064 or faster you won't hurt the op-rod.

Checking three manuals, I get 53.6, 53, and 52 grains as maximum.  I don't see any reason to beat yourself up by chasing maximum velocity though. (I'm assuming you are only shooting at 200-300 yards)  I'd start at 48 grains and work up to around 50 and see where you get the best groups.   Somewhere around 49.5 grains will likely be the most accurate, but every gun shoots a little different.

If you are using mil-surp brass back off by a full grain.