I've played some pickup games with 3145 equipment, i guess i would say it would vary and depends on who your fighting.
Not getting into Battlevalues or how companies are structured differently in the Dark Age and just looking Mech per Mech with only the tonnage mattering.
A generic force, what your describing could weapon wise handle some forces of equal strength. Not everyone packing the special equipment. Periphery has some Star League tech and some sprinkles of advance tech by 3145 if you look at the RAT as some sort reference on who using what.
Couple examples:
I would say force your using would be given a 30/50 chance of success if it were straight up fight without tactical tricky and bumbling on either side. If your force of Mechs ends up fighting typical Draconis Combine forces, number units have Heavy Ferro-Fibrous armor, cutting damage inflicting to them in half. 3025 era Mechs sometimes have thin armor in comparison to many units. Number 3145 units are fast, DC units even with slowed down by Heavy FF Harden armor are fairly quick, though number of the Mechs have less weapon on average (This my opinion) per unit than you find on some bigger Mechs of 3025.
You have Capellan force from 3145, they move fast, their packing heat-generating/still PPC worth damage causing Plasma Rifles in many cases. Then you have guys with the TSEMP Cannons which have go chance mess up your Mechs with penalities or worse on rare occasion shutting your guy down.
That all said, your old force of Wolverines, Warhammers, Marauders and etc still are viable force, it just depends on how you use them against some these units with their neat little advances. Just don't go in flighting like a Lyran and think raw firepower is the answer to hightech trickery.