CHEAPest way to convert rear axle bolt pattern to big bolt pattern???

Hello all,

I have a 1964 Valiant, slant 6 motor with an A-904 trans (I think). Its an automatic, its slow, and I'm keeping it that way. I assume it has the stock rear-end.

I'm upgrading my brakes in the front to discs from the 73-76 a-body. That involves the ~11 inch rotors with slider type calipers. This also involves having the front bolt patterns become converted from the small bolt pattern (5x4) to the large bolt pattern (5x4.5)

The fronts are not what concerns me. It is the rears...

What is the cheapest safe way to convert the rear axle to the large bolt pattern. This is a cruiser, no crazy V8 torque, I'm staying with the slant 6, and I have no interest in swapping in a huge new axle, unless that is my only choice. My '64 has a narrower rear axle than the newer a-bodies, so most newer mopar rearends will not swap right over. These are my options as I understand them:

1) I could get custom axle shafts, that are the proper length with the larger bolt pattern, and use drum brakes from something newer.

2) swap over a newer entire rear end and have it cut down, and the perches relocated, etc (ugh)

3) use an "adaptor" to convert the lugs from 5x4 to 5x4.5. Do I still have to get new rear drums? Is this safe for my mild use?

4) have a machine shop modify my current axle shafts to remove and install new lugs at the desired spacing, redrilling the drums at the same time. Is this safe for my mild use?

-Reminder: Ease and safety are my primary concerns. This is no drag car, it is just a fun crusier. BUT, I don't want to have to worry about the wheels flying off on the interstate.

I've read so much and most seem to recommend an axle shaft swap or a modified rear end. Many posts go nowhere or don't have much follow up so I'm always left wanting a little more. Most questions aren't about such an early model either.

Thanks for your patience, and tell me what I can add to make your assistance easier.