Along with Grassroots and Classic Motorsports I also read:
Practical Classics
Vintage Motorsports
And the NY Time "Wheels" is usually good too.
A great tech read (and even some car related stuff) is Make magazine.
I also read Machine Design and the SAE magazine (my job pays for these).
I do miss the John Bond-era Road & Track. With Manney, Rob Walker, Stan Mott and others.
And I actually remember reading C&D it when it was Sports Car Illustrated. This was back when C&D had Gordon Jennings, Warren Weith and Dicky Smothers writing. And later Csere, Yates, Bedard, Sherman, Steve Smith, P.J. O'Rourke and others. C&D was a great magazine. Now it just suitable for the bottom of bird cages in my opinion. This is almost true for R&T too.
Peter Egan's stuff is all online ~Here~