[Retros] Let us double the stakes?

[mr.mip]

Well, my friends Joost and Dupont (....or was it Dupond? Hard to tell
without seeing the moustache). Why not an SPG with both White and Black
having a 6-pawn column side by side?

Here is rather famous one:

Lauinger,Frangen,Kisljak :
Feenschach, No. 2201, 07-10/1977

wKd1,Pe2,e3,e4,e5,e6,e7/bKe8,Pd2,d3,d4,d5,d6,d7
4k3/3pP3/3pP3/3pP3/3pP3/3pP3/3pP3/3K4

Stipulation: Provide the shortest proof game to above.

The famous 'Trojka' L-F-K gave the solution with SPG 32.0, but the
eagle-eyed readers of the magazine '64' were able five years later to point
out another SPG 31.5. Is there still slack somewhere?

mr.mip

Spoiler(s) below
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Composers' SPG:
1.h4 g5 2.hxg5 a5 3.b4 axb4 4.Nf3 Ra3 5.Rh4 Re3 6.dxe3 h5 7.Qd6 exd6 8.Rd4
h4 9.Ne5 h3 10.g4 h2 11.Bg2 h1B 12.Bc6 bxc6 13.a4 Ba6 14.a5 Bd3 15.cxd3 Be4
16.dxe4 f6 17.a6 fxe5 18.a7 exd4 19.a8Q Qe7 20.Qa5 Qe6 21.Qd5 cxd5 22.f4 Nf6
23.gxf6 Be7 24.fxe7 Rh5 25.Ra3 Rf5 26.gxf5 Nc6 27.fxe6 Ne5 28.fxe5 c5 29.Kd1
c4 30.Rd3 cxd3 31.Nc3 bxc3 32.Bd2 cxd2
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And Readers response:
1.h4 a5 2.b4 g5 3.hxg5 axb4 4.Rh6 Ra3 5.Rd6 Rd3 6.cxd3 exd6 7.f4 b5 8.Nc3
Nf6 9.gxf6 bxc3 10.a4 h5 11.a5 h4 12.a6 h3 13.a7 h2 14.a8Q h1Q 15.Ra4 Bb7
16.Rc4 Bf3 17.gxf3 Nc6 18.Bh3 Ne5 19.fxe5 bxc4 20.Be6 fxe6 21.Qd5 exd5 22.f4
Qe4 23.dxe4 c5 24.Nf3 Rh3 25.Nd4 Re3 26.dxe3 cxd4 27.f5 Qe7 28.Qd3 Qe6
29.fxe6 cxd3 30.Bd2 Be7 31.fxe7 cxd2+ 32.Kd1