I know this isn't what you want to hear, but ...
Those are excessive doses of 5-MAPB and you are probably asking for trouble if you continue with that pattern of use. Do you have a large tolerance from frequent use? If so, I'd strongly recommend taking a long break of at least two months before trying again. If you don't have a large tolerance from frequent use, I would consider the possibility that either your product is not very pure or 5-MAPB just doesn't offer whatever it is that you're looking for.
You said yourself that that there are very few, if any, reports on this combination. If you haven't yet tried 5-APB on its own, why not try that by itself before diving into uncharted territory? Doing so would give you a better idea of the experience than someone else's opinion will, and you can make a personally informed decision about how well the two would go together. Besides, 5-APB is a pretty complete experience in its own right; you might decide that it doesn't need anything else.
If you insist on going through with this combination, reading the reports you mentioned of 5-MAPB combined with 6-APB are probably your best resource for deciding how the two will go together. 5-APB and 6-APB are fairly similar in their effect profiles and duration of action, although 5-APB is more potent by weight (which is to say that 5-APB requires lower doses than 6-APB). On a final note, please keep your doses on the low to moderate end of the spectrum any time you try a new combination of chemicals for the first time.
Your best bet if you must go through with this combination (and I still don't really recommend it) would probably be to start with a moderate dose of 5-APB (80-100mg). There is a long two hour come-up with 5-APB, followed by about a two hour plateau and a slow, gradual decline to baseline. If, after two to three hours, you still feel like you need more, only then consider topping up with a small dose of 5-MAPB (about half your usual amount or slightly less; I would recommend no more than 60mg). But please, don't go into the experience having convinced yourself that you must go through with the combination.
Stay safe.