The core is usually 3, with 9 next and 5 last. So I guess I’m actually 395 rather than 359.
What I was saying on the first post slowly starting to happen with people "sub-tweeting" me and all and for personal reasons I am not really under much patience for this, so I shall just rest my case here with final "advises".
You are right for being worried about MBTI and tri-type being dissimilar. Linking systems can help you a lot, and the reasons you must spot incompatibility is to know if you are not answering the tests as two different persons or having two different images of yourself, which is inaccurate. My last example was on reddit where I explained why ISTJ can't have a high-very high Openness to Experience, because the person would be imaginative and unimaginative at the same time (I had mentioned also 2-3 more contradictory traits, which I don't remember).
But I already got deep on that subject and I must reinforce: 3-9-5-[7] can fit basically any MBTI. Core 3 does take IXFP out unless you are quite unsure of it and think you might be 9 as well. This is also a case (and I bet 30-50% of people are like that) that none of the core MBTIs will really actually describe you well - you should properly see yourself as a mix of some MBTI, at least two of them.
You can still use the Big 5 to assist you on the journey, which I do recommend a lot (it works quite well as a supplementary and you can think the other systems in Big 5 terms if you want), and in that case it would be good to draw which are the normal signs of each type (remember, you are not 'normal' inside each type, so you may deviate a little). Oh, also note that on COVID days, specially if you are on quarantine, Extraversion and Openness drops (this is a known pattern for flu):
E=Extraversion
A=Agreeableness
O=Openness to Experience
C=Conscientiousness
S=Emotional Stability
(this is also called OCEAN, I just put it on a different order)
ENXP: High E, High O, Low C. High O is the most critical, some can be high C or have 20-40% range on E, specially if you are going by the functions
Core 3: High E, High C, Low A. All are sort of equally important aspects of 3.
Core 9: Low E, High A, Low O, Low C, High S. High S is the most important aspect, Low E and low O are the least relevant, and Ns 9s exist significantly and generally are not low O. Also, 9 is supposed to be more close to an ambivert rather than Introvert.
This is it, hopes it helps, have a nice journey!
EDIT: I also forgot a few things...
When picking up an enneagram and MBTI specific combo, try to match your close borderlines. So, for example, ENFP 5 has both E and F pulled down due to ennea 5, and it is closer to a pure Ne-dom with slightly e (almost hybridizing Ne and Ni types). ENFP 3 has a predicted F/T borderline, while ENTP 9 doesn't have much prediction but it is slightly pulled towards ISFP, expected to be ambivert (because MBTI & Jung typology misses some important aspects of 9).
Another thing, when your ennea and MBTI combo are not super common, looking for fictional characters with the same combo and using which characters you relate the most helps (it did to me). You can google the characters and look at their descriptions on the fandom, most of them (if anime, almost all of them) have a 'personality' tab on their description and a group of characters description may describe you better than any MBTI/ Enneagram core/tri-type in isolation.
I also forgot to put the link to my own converter from Big Five to MBTI. If you use it, you should notice the first 3-5 results and I would recommend to rule the last 6-10 ones out, don't be too attached to only the first one:
https://www.quotev.com/quiz/12999568/BIG-FIVE-to-MBTI-converter-quiz
