DOC_Agren, MoneyLovinOgre4Hire, Starfox1701, mbear, and glitterboy2098 thank you for addressing the question at hand.
Based on these answers I will be going with there is no substitute for cubic inches. While the TSM would be my first choice the ability to have both 'Mechs in it's sweet spot is to chancy.
mbear, the plan is for this 'Mech to provide cover fire for the melee one so it will be built primarily around long range weapons, most likely energy so that it can lay down fire and not have to worry about running out of ammo from missed long range shots. But that is a discussion for another area of the boards.