Evan, balancing your Taurus with a bigger/heavier Engine is no problem with such a long tail, and I think you know that already!
First you can put your battery back, and if that is not enough 1/3 of the weight in the tail to compensate noseweight will do.
I have on this moment a MVVS .61 and no weight, balance is good. HB 61 was also no problem, with my OSMax 61 FX battery in the receiver compartiment.
Do you know that a OS Max 0,46 AX is as heavy as a OPS 0,61 both with muffler!!

I did make a drawing for you from the fuselage of the Oldest Taurus on Earth, The fuselage is not only is less high, but also much shorter on the nose.
When Ed did make the tailplanes (stab and fin) thicker, profiled and sheeted he could not get the CG on the right place, look to the red square, that will be clear.
He did has to do nearly 4 times the extra weight of the tail in the nose, that was more than the weight of your engine Evan!!!!

He could lose this problem simple with only one action, swept back wings, straight TE. We see the result in wings #3.

And the fit of the Old wings?
Did you ever see the wings back of the MAN Magazine Taurus after the Internationals in 1963? I not!
After the Internationals we only see the taurus of auction 2 in several configurations. So, maybe they already were destroyed!
And!
Do not mix up stories and statements, we know now there were two Top Flite Taurusses on the moment of the crate, and they were identical, from Ed and Dennis.
But, Ed also did make the swept back Taurus as the original contest Taurus, oldest on earth and so the fuse was less height, narrower (post116), with shorter nose as the Top Flite Taurus so not the same. And we know now they together were in the crate!
The fuselage of this contest Taurus we see later in the auction 2.

And of cours Top Flite did made a extra piece on the nose of the Taurus so you would not have directly problems with your CG even with a light modern engine.
Let me know what you mean with "we"?
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Not only that, but we have eyewitness statements that
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Cees