As I recall it, ICT were well aware that their manager was hot property and offered a long term deal, as an incentive to turn down the Utd job. The key terms of it were agreed in principle with Pele but the contract was never signed.
I'm not sure if this was just because of the time it takes contracts to go through lawyers and agents, or if the club were slow, or if it was because Pele knew that the Aberdeen job was imminent and he wanted to keep his options open. (It was widely rumoured that having initially agreed to go to utd he changed his mind at the last minute because he was advised by someone to sit tight and the Dons job would be his, but I don't know if that is true. Hopefully his book will clarify!)
I believe though that despite the absence of a signed contract Pele ensured that ICT were fairly compensated, so it didn't make any difference in th end.