SB standard or billet starter ?

standard will and should be fine, you can even get good service from the $50 rebuilds from rockauto. i pushed one into servoce 10 years ago and have never looked back
mine is a 12:1 CR I6 using a 25 mm pinion on the starter so i loose on CR but win on gearing
and probably average out same as you.

the issue with these starters is that they will quite hapilliy start your motor when they are not quite installed properly. that lovely front of tooth profile you get with a denso means its gonna engage to some extent with the ring gear whatever angle it approaches at.

I'm not saying you haven't installed it properly i agree you might just be unlucky BUT having not installed one properly myself (my standard one, hence the need for replacment) i know it can happen, and then the added akwardness of getting the new one to seat.... you'll see where i'm coming from....

1) if you use the bellhousing seal for an original starter it can intefere with proper seating. you need one cut for a denso or remove it and suffer grubby bellhousing.
2) the nose on the new style starter is more of a push fit into the bellhousing register than the old style. you can get the starter in with the nose hung up on the register at the base of the dome in the bell and it feels like its in right, but its not you wont get the reassuring clonk if its not.
3) on some blocks mainly big blocks there are bosses used in casting that stick out and will not allow the starter to seat due to pressure against the motor body or solenoid. these bosses can be ground down a few thou to faciltate a proper perpendicular to flywheel/ring gear mounting

if any of the 3 above occur it leaves litterlly a fraction of an inch gap between the bell houseing face and the starter face at one of the mounting points. meaning that the lug on the starter mount is stressed just by being mounted and the nut done up. Use of the starter in this position smashes the nose off eventually. the nose casting is thinner than the mounting lug casting so it goes first.

starter mounted.... and starter mounted with a couple of thou last "Clonk" into position are two different things.

you can dress the tapered end of the D spigot on the nose of the stater with a file and grease the end thinly to help
you can blast out the register in the bell with a air or with care WD40... try not to get it on your clutch.... althogh it does burn off.

the contour of the "jaws" of this starter are tighter than standard starter and getting it round the ring gear with 1 mounting stud engaged is harder

this starter also came on bell housings with 2 different sizes of mounting stud
a big hole starter on a small stud bellhousing needs just a little more care in mounting,
the section of the starter that follows the edge of the bell housing should follow the edge of the bellhousing. slightly off centre is not great, but properly seated but off centre doesn't tend to cause this problem . infact its easier to install the big hole starter on a small stud housing more wiggle room around headers etc.

if you are using a steel scattershield type bell. it may not have any support beyond the 2 mounting stud/bolt. no spigot in the bell. in that case the starter mounting surface of the bellhousing is twisting under the torque of the starter and thats why it breaks. it pushes the nose outwards away from the ring gear and the end of the stater body into the block and snaps off the nose. according to forum posts one manufacturer produced steel aftermarket housings that did this, for quite a while, but i've seen no one complaining for 10 + years. no experience with this, just hearsay that may be relevant.

id suggest that unless you are starting a massive race motor spending $100s on a nice big red one with lightening bolt stickers on it, is not necessary

you can of course repair that broken starter. you just need to find a company with access to the denso spares catalogue and get them to get you a new chrysler spec nose.

or you could probably cut the remains off and run it as it is....it would get you going until new one arrives. i like the 3rd mounting point myself if the nose is cast but not the end of the world for short term use

Dave