Earlier you said you would upgrade your cloaking on your storage planets when u can, and you haven't mention energy needs, so i would researching cloaking first.

although im only rank 31 and a lot of people will disregard this, why not swap to konqul builder to gain the extra credits until you unlock taltherian, then swap to talth excavator? its not like your staying with builder forever and the boost to credits is always nice.

Good luck in the future.

IMO your upkeep is killing you. NPC for purifiers and build toxics asap. Your upkeep really shouldn't take any more than 8 hrs of your daily production. Keep working at talth but with your energy pool that will be a long while. Expand your energy while you NPC.

Get more engineers, downgrade your cores (not your relays). You'll save sooo much upkeep. I have about your energy at 350, so increasing the rate at which you pick up engineers wouldn't hurt much either.

Its not the reactors that need a downgrade. Would only save .5b. And he needs all the e he can get for talth.

Its those thrusters. At .5b each... Downgrading dampners should help too.
Might be biased as I use those but meh.

As far as MSBs go, just save them up for Polychoron Vaults, even if you don't have it unlocked yet, it'll do you good to have the resources to make a fair amount when you do.