Never seen anything gained by taking timing out in high gear on an NA car and have tried on a few different cars. It's possible had other issues, we went from a single 4 to a T/R and it wanted less timing. We had run the single 4 up to 38 Degrees max timing. Since it ran just as well / slightly better with less timing with the T/R we left it at that. Does seem to cruise better with more timing in the mid rpm range though 
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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