Just a couple of things to keep in mind. One, when you seek to enter an order or congregation, they are just as much vetting you as you are discerning whether you fit with them.
The most important thing when joining an order is whether or not your charism is aligned with that of the order. If you go to an order just because they have the Tridentine Mass, but have nothing in common with the charism of the order, both you and them will be extremely unhappy with the choice. In fact you may not even be admitted to simple or solemn vows; this happened a couple of years ago at the monastery I’m attached to; a young man wanted to join because it was the most “traditional” religious house around with Gregorian chant (but all in the Ordinary Form); the novice master flushed him out because that was not why you join a monastery: you join a Benedictine monastery to become a Benedictine above all else. The entire community gets to vote on whether you can ender or not after postulancy, after which you take simple vows and enter the noviciate. Simple vows may be renewed but not indefinitely. The community will vote again on you when it is time for solemn vows.
Similarly, if you have a profoundly, for example, Benedictine view of life, you’d be happier in a Benedictine monastery with the new Mass rather than another order with the old Mass (and as a bonus Benedictines usually do a splendid job with the liturgy whether in the old or new form).
It’s very much like a marriage, a two-way street! You will be spending the rest of your natural life with these folks. You will be seated in the refectory in between the person who entered before you and the one who entered after you. It may be someone who drives you crazy by slurping their soup, and you’ll have to put up with it until one of you dies first. It’s a big adjustment, as you will be entirely surrendering your will to God as represented by your abbess or superior. If she says go scrub the bathroom floor with a toothbrush, you will be scrubbing the bathroom floor with a toothbrush.
