I accidentally deleted somebody's message but believe the question was
whether Bill Fisher's "hot rod" book (1970) has anything on dual ports. It
does. He writes (p. 49):

"1968-70 fastback, squareback, notchback "Variant" engines have dual-port
heads and 1600 cc displacement. All 1971 VW's have these heads.
[...] ultimate configuration for high performance. [...] These heads, P/N
311 101 355D, cost about $45 each at the VW store. Intake-port area on
these heads can be vastly enlarged by the "square-port" technique
developed by Gene Berg. These are "the" heads to use for all-out
high-performance VW engines, [...]"

-- 
Sami ('75 Westf.)
dakhlia@wuecona.wustl.edu
http://wuecon.wustl.edu/~samid/