Brolli has never been "USSJ", this form is Unique to Brolli and always refered to as LSSJ, Since his size and body increases but speed is still high, where as USSJ size and body increases but speed is cut down - USSJ Trunks vs PCell for example. i have never read any bios or seen anything refer to this form as USSJ.
Taken from the DB wiki,
"Unlike other Super Saiyan forms which cause the inexperienced user to suffer exhaustion, this transformation maintains a constant flow of energy as a battle is prolonged. As a result, this form requires no ki consumption, gives Broly phenomenal strength and speed, and constantly raises his power level as long as he remains in the Legendary Super Saiyan form. Additionally, the irises and pupils in his eyes seemingly disappear, giving an even more menacing look than most Saiyan transformations. During one scene in Broly - The Legendary Super Saiyan, it is implied that Broly must release some of his power in order to maintain his physical body's stability, meaning that there initially is a limit to how much his power level can increase at one time (though he seemed to have overcome that setback when he attacked Earth). The Legendary Super Saiyan form erupts from underneath the flesh of his previous form.
This form is also one that is quite unique to Broly (as it is a genetic trait), as he is the Legendary Super Saiyan. It is a form that has very little disadvantages and allows Broly to overwhelm his opponents. Broly's power level not only shoots upward tremendously, but it also steadily increases as long as he stays in this form, so the longer he fights the stronger he gets. Since the power level in this form is so vast, Broly has been shown to take extremely powerful attacks without so much as flinching. For example, in his first appearance, Broly fought two Full-Power Super Saiyans, 2 2nd Stage Super Saiyans, and a Super Namek all at the same time and was in control of the whole fight, with his opponents being unable to hurt him in the least. "
Anyways..., Im going to rebuild most of the upper body, more towards your ref Denz, but the arms are prob gonna remain the same pretty much, as i like the massive bulk size from most refs, and cause Ski and I will look over proportions after XD