I always use VITON seals wherever possible, these are vastly better than std ones, as they are meant in high heat loaded applications, and have much higher clamping pressure than std seals,(which should have been fine).
All the viton ones I use have always had a wire that was in such a depth of moulding that it can't even be got out when you try, so would never fall out, when installing.
On crank seals I always plastic them in when inserting, a thin ring that goes between crank and seal, then just rotate whilst pulling out gently, with everything oiled.
tabetha