The Grumpy Grease Monkey mechanical engineer.
the guys a bit annoying but the info in the video, is basically valid
and yeah,you tend to get what you pay for,
and theres a great deal of lower quality, mostly imported crap auto parts,
on the market that preys on , and sale depends on.
the uninformed, mass of the public for sales,
and less than knowledgeable consumers neither knowing how,
to go about checking the component quality, fit and finish,
or checking port alignment and gasket alignment
,or component assembly care , taken during manufacture, or component quality.
and how your intake manifold compares goes a long way,
toward preventing potential problems,
not all cylinder heads and intakes or gaskets are interchangeable, or compatible if matched in use.
and as always a great deal more info is in the links and sub-links
COMMON SBC INTAKE PORTS
felpro # 1204=Port Size: 1.23" x 1.99"=2.448 sq inches
felpro # 1205=Port Size: 1.28" x 2.09"=2.67 sq inches
felpro # 1206=Port Size: 1.34" x 2.21"=2.96 sq inches
felpro # 1207=Port Size: 1.38" x 2.28"=3.146 sq inches
felpro # 1209=Port Size: 1.38" x 2.38"=3.28 sq inches
felpro # 1255 VORTEC=Port Size: 1.08" x 2.16"-2.33 sq inches
felpro # 1263=Port Size: 1.31" x 2.02"=2.65 sq inches
felpro # 1266=Port Size: 1.34" x 2.21"=2.96 sq inches
felpro # 1284 LT1=Port Size: 1.25 x 2.04''=2.55 sq inches
felpro # 1289 FASTBURN=Port Size: 1.30" x 2.31"3.00 sq inches