Using Gemtria for the purpose of determining whether two items have a relationship, are you allowed to match one method with another. For example, Absolute Value with Mispar Katan? Or AtBash with an AlBam? And so forth.
I believe I have found your answer. The Tikunei Zohar explains that the concept of reduced value is related to the spiritual world of Yetzirah. On that basis, a relationship can be established between these four forms of calculation, the four spiritual realms, and the four letters of God’s name. I found this on [inner.org]
Your wording, if matching is "allowed", is puzzling if you mean the word literally, as in halachah, for why should you not be able to relate two cognitive ideas, even so much as to say they are irrelevant to each other, so I assume you mean if such matching can teach something, or has been used to teach something by our sages or rabbis. Certainly gematriot don't render halachic conclusions, for that would be absurd.
My answer would be, based on a natural Torah-based perspective, of a simple but observant and learning Jew, that of course such comparisons are permissible, for anything mind-related that Torah provides is fertile ground for further thought.
Since gematria is an alphanumeric system, it is best used within a mathematical framework within which the results associated with the use of gematria must be consistent. The framework must necessarily include axioms from which we develop definitions, lemmas, theorems, and corollaries. Indeed, the Method of Gematria can be precisely defined as follows:
Let V_1 and V_2 be two verses in the Bible. Let N_1 be the total gematria of a set of words in V_1. Let N_2 be the total gematria of a set of words in V_2. It is possible that V_1 and V_2 are contextually or thematically linked if and only if N_1=N_2.
This definition refers to words or expressions in the verses that are contextual or thematic. By Collins English Dictionary, the context of a word, sentence, or text consists of the words, sentences, or text before and after it which help to make its meaning clear. So once the Method of the Gematria establishes the association (N_1=N_2) between the two verses, V_1 and V_2, then several verses before and after them may need to be consulted for a better understanding of the association. Also, by the same dictionary, in linguistics, the adjective thematic denotes a word that is the theme of a sentence. In grammar, it is of or relating to the stem or root of a word. Very often, there is a need to consult Strong’s Concordance and the Hebrew and Greek lexicons to fully understand the association between words that are thematic in the Bible.
I am happy to expound further.