Optional Preferential Voting in Queensland and NSW often acts similarly to FPTP, with a majority casting just a first preference (especially for one of the two major parties). Consequently, I think that the way the parties in those states have responded to the introduction of OPV would probably be likewise played out federally if there was FPTP introduced in 1975.
The Coalition would have probably reached a "no three-cornered contests" agreement within a couple of elections. This would probably lead to a stronger National Party presence, because there have been seats won by the Liberals when National Party MPs have retired (Farrer, in Western NSW, following the retirement of Tim Fischer, for example). With FPTP potentially costing the Coalition seats in cases where the Liberal and National Parties ran against each other, they'd probably be less likely to contest them upon the retirement of Member (present deal is that they don't run against incumbents from the other party, but if a Member retires, or if it's a rural Labor-held seat, both parties may run - but obviously preference one another ahead of any other candidate).
So FPTP would probably mean there would be seats uncontested by the Liberals in rural areas upon the retirement of sitting Nationals, thereby giving the Nationals more seats in the current Coalition.
I don't think it would significantly alter things for minor parties, unless there were also changes to the Senate, because PR-STV in the Senate makes it easier for minor parties to get elected there, even if they don't win House of Reps seats. The 2010 election was the first time a Green was elected to the HoR at a General Election (Michael Organ won Cunningham at a by-election in 2001, or thereabouts, but the Liberals didn't contest that seat and it was a by-election). FPTP would make it less likely for the Greens vote to rise in the HoR compared to real life, and they relied on Liberal preferences to win Melbourne in 2010 anyway, so although they'd be less likely to win a seat, that is just one seat in one election where it would actually make a difference. Of course, they could use sort of a "spoiler effect" to threaten Labor - sort of doing a deal like Elizabeth May and Stephan Dion in 2008, where there was no Liberal candidate in Central Nova, to maximise her chance of winning, in other words, perhaps persuade Labor to gift them a seat or two, rather than splitting the left-wing vote in Labor marginals.
One Nation would have benefited from FPTP in 1998 - I'm pretty sure Hanson led on primary vote in Blair, but Labor preferences handed the seat to the Liberals. Possibly other seats, also.