Hub Bolt Sizes

[Hewfil1]

Hey guys, finally got some spare money and time again and I decided to delve back into slowly getting my 1974 K10 back up to snuff. Went to do the brakes and planned on putting all new grease and bearings in and ran into a common issue of the bolts that hold the locking hubs on being seized.
I've hit them with heat, penetrating oil, even tried an impact screwdriver. So I figure I'll resort to drilling the heads off the bolts so that I can get them apart to do the brakes.
I keep seeing conflicting answers regarding this so I was wondering if anyone knew what the length, and thread pitch of the bolts that hold the hubs on are. It's a 1974 K10 as I previously stated, and has manual locking front hubs.
Any help or even some tips/tricks regarding this whole process would be greatly appreciated, thanks!