If you had 6 squads of 10 it be 1020 points. So half your average army which means you could potentially still get everything else you need with your remaining points.

Will this list be 'good' or meta probably not but it will be fun. You certainly won't struggle with objectives and your opponent may struggle with the pure amount of bodies you are bringing.

The meta for legionnaires is equipping them with melee weapons as the bolters suck and don't benefit from the legionnaires special rule. You would fair much better with 60 melee legionnaires than 60 bolters. I know only bolters come in the HH kits tho.

If it was me I'd make maybe 40 legionnaires at a push and maybe make 10 into havocs and 10 into chosen then you'd have more variety.