I agree. Do not alter the circuit. Just replace what TRUELY need to be replaced with exact spec components or closest value.
This is not quite vis-a-vis the McIntosh, but if Clicks will allow:
'Original' can sometimes be altered to advantage. E.g. power supply filter capacitors (electrolytics) of 40+ years ago were relatively LARGE things and the reliability not that of this day. One must not underestimate development in materials science. When I think of cathode bypass capacitors, 20µf-50V types of the time were fairly large and expensive. In e.g. the Quad II I replace the KT66 cathode bypass cap with a 1000µF-50V type, in the interest of approaching fixed bias conditions during music signals, giving 16 - 18W undistorted peak output. It still fits nicely in the old capacitor's space. Would Peter Walker have minded? I think not; he would have done it in his day had it been practical.
Similarly I replace the 16 + 16µF-450V power supply caps with a 50 + 50µF-500V pair. But it is very practical to open the square 'tin' in which the original is housed, take it out and put the new one inside. Thus the appearance resembles the original. (Just put a sticker on there that it has been modified, or some other person will throw it out thinking it was still the original.) Likewise other, mainly bypass caps, could be replaced with larger values and higher voltage types (I have never liked a 6V cap) to advantage. For myself I do not think this alters the classic value of the instrument.
Sorry for the hi-jack; the intention is a general idea of what I would consider advised 'alterations' in contrast to circuit changes per se. (And then the praises sung in favour of boutique parts .... but that is another story.
'Audio quality' my foot.)
