The Rhodesian Bush War passed without a decisive 1975-style conventional campaign. Of the two main guerilla organizations, it was the Ndebele, Soviet-favored ZIPRA that placed more of an emphasis on conventional operations, compared to the majority Shona, China-favored ZANLA’s “people’s war”. A combination of largely successful preemptive strikes by the Rhodesian military and a (smart) focus on inherent strengths than weaknesses by the opposition meant that the large battle never came.
The common wisdom about such an operation “Zero Hour” (as one code name for it was) is that it would be stopped with ease (although it does not help that most surviving prominent sources are either from the ZANLA-veteran regime or former Rhodesians, neither of which has an incentive to talk up their opponent). But even if the first such offensive was stopped with ease, the rebels definitely had the people and enough hand-me-down aid to try multiple times.
Such an offensive would feature the fairly light Rhodesian military against an opposition that would have at least T-34/85s, BTR-152s, appropriate artillery, and even rumors of fighter aircraft. (If said fighter aircraft could disrupt the deployment of the infamous Fire Forces, it would not be good for the Rhodesians). It can obviously be played with any kind of wargaming ruleset that can handle early/mid Cold War equipment and formations.