Have had a bit of experience with the Sav. M24 over the years. They can be a great little gun, as far as mounting a reciever sight.. I think that it would depend on your main usage objective.

If no wingshooting is required then a reciever sight would be a good alternative, with respect to aging eyesight, sight radius. At least reguarding one barrel - usually the rifle barrel, as these are not "regulated" the rifle barrel may, may-not print close enough to shotgun patern be usefull.

Drilling and taping the reciever would be my preference over the "Tip - off" dovetail method, as these can slide under 20ga. recoil. ( the dovetail option may not apply in your case, as you mentioned yours was smaller than standard)

Accuracy will most likely meet your demands, only range testing of your gun can answer this question. If no percievable movement between the reciever and barrels is noted, barrel vs reciever mounting should not be an issue.

Large vs small aperture? Depends upon lighting and speed of use, as well as eyesight, but these are inexpense - try them both, also dont forget that these can be removed for an even larger "gost ring" opening.

Durablity should not be an issue, but a back up (folding leaf) might be wise.

As to the posable replacement of the front sight? Savage has produced many varitions over the years, with front sight heights from Very low, (.25" ?) to pretty high (.400"-.500"), If you have a higher one you may "get away" with it.

On the flip side of the coin, ( aka wingshooting) the only reasonable approach (IMO)would be a folding leaf sight, folded out of the way.

Just my opinion, your milage may vary, best of luck to you.