Maybe it's just me, but another bad thing with the official "heart attack hill" is the P450 from Skuce to L.Nadine immediately before the actual Heart Attach Hill from L. Nadine to L. Osler.... we were coming south towards the Nip and Those two portages back to back were deadly. the 450 is not super difficult, but does also have some decent elevation change rather quickly.
I remember collapsing, leaning on an erratic, at the top of the H.A. Hill, questioning why I put myself through this... fond memories.