Savage 'Upgrades'
Hi guys - I've seen this thread for a while and decided to add a bit. I've done several things to my 64 to improve functions. Pics for all are below.
First since you're focused on the charging handle and mag release, I took an 1" self-tapping bolt - 1/4" I think - and rounded the hex head on a grinder. Then I took a 3/8" nut and rounded the hex on this and slipped that on the bolt, so it's loosely moving. The bolt then is screwed the existing charging handle. It's stayed there for about 5 years now.
For the mag release, I drilled the existing release with a vertical hole, most of the way thru. I forget the size but it is to insert a short bit of coat-hanger wire, about 3/4" long, with a 45* bend toward the front. I secured it with a bit of JB weld which 'softened' the contour. This too has stayed in place for about 5 years and works easily w/o sticking out so far like the DIP release.

I also 'relieved' the mag well, stock area, and bottom metal to improve mag insertion. Just a lot of hand filing so I wouldn't take off too much w- a Dremel.

I got the MCarbo spring kit which helped the trigger pull, but the used a bit of 'clik-pen' spring (about 1/3 of one) on the trigger return. These two 'spring mods' took off about 2# pull. I lightly 'polished' ALL internal parts (including the Sear Pin AND Hole -see Pic) to reduce friction, careful NOT to change any critical angles like the Sear contact area. The trigger now is around 2-3#, fine for a plinker. :bthumb:
Last, I'd suggest that you load a snap-cap as last round in your mags, to avoid 'dry-fire' damage to the firing pin if you lose count like I do. I can get by with 9-rounds and I usually just load for 5-round groups anyway . That took me a year or so to figure out, after ruining a pin. Luckily, Savage sent me a new one when I
called them. :bthumb:
I hope this can help you all a bit -I know it looks Bubba, but saved me about $100 or more AND helped to 'feel' something more than spending $$. YMMV

Last pic of my rifle - came with flash suppressor - Not a Can ! And Cheek Pad under $10.
I can now shoot under 1" @ 50yds with 'Average' ammo like CCI-SV or SK+, using a 4-12x40 Tasco scope.
If I take my time - it's hard to control Fun :gun4:
Charging Handle
Mag Release & Mag well
Better pic of Mag Release
Trigger Return 'Clik-pen' Spring
Sear Polished #1
Savage 64 pic