You are attempting something highly artificial: providing an English equivalent to all the parts of a verb.
The trouble is that many of the parts are used rather differently than any so-called English equivalent. This is especially true of the participle and gerund/gerundive than any other part of a verb. English has no future participle in the way Latin (and ancient Greek) has. We have to concoct one as best we can. The participle and gerund or gerundive forms lent to Latin a taut terseness that is hard adequately in English. Most famously:-
Morituri te salutant
as spoken by gladiators to the provider of the show (most notably but not uniquely the Roman emperor of the day). Just three words. “Morituri” has no stated subject, because it is implicit in the gender and number of the participle. Moreover, there is no equivalent English tense. The best we could do would be
About-to-dies salute you.
But that is just not English. Even sticking in the definite article doesn’t help much.
Those about to die salute you.
That is what in effect is meant, but it lacks the punch of what the poor devils said at the time.
Moreover, how you translate a participle into English will depend on the context. Much of the time, Latin participles are better rendered as clauses, particularly temporal and causal.
Pulsaturus stetit - probably means: on the point of punching he stopped.. Or something like that. We could express this as
He was just about to throw a punch when he stopped.
But Latin has another use for the future participle: to express a future infinitive with the verb to be (esse). This is important because of its role in reported or indirect speech. So in Latin the sentence “The thief said (that) he would punch me” we have:-
Fur dixit se me pulsaturum esse. or in literal English, The thief said himself to be about to (or going to) punch me.
So about to punch or going to punch or being on the point of punching are some or the ways to indicating the futurity of the participle. But only the context will allow you to decide how to render it into authentic English.
Latin (and Greek), for all that it has in common with modern indo-european languages, exists in significant aspects in a different linguistic universe. So the translator from Latin to English (or vice versa) requires us to ask ourselves “what is really being said, and how would that be said in English (or French or German or ....). But the learning of wooden decontextualised equivalents like being about to or to be about to are a necessary first step. After that, the student needs to read as much actual Latin as possible, with the question “what is really being said and. how would I say it in English?” in mind. At least, that is how I taught it.