I have tried part of that way to Kelantan as follows:-
Singapore to KL.
KL to Karak, Gambang, Pekan, Kuantan Pahang,
Kuantan to Cherating, Rantau Abang, Marang, Kuala Trengganu.
Kuala Trengganu to Tumpat, Kota Bahru, Kelantan.
Kota Bahru to Gerik, Ipoh, Perak. (very winding road certain stretch)
Ipoh to KL.
KL to Singapore.
It was quite an interesting trip.
The Kelantanese are keen to study Chinese so that they can work for Chinese bosses as they said that the pay is higher and they are being treated better as an employee.
In fact, we came across the locals speaking fluent Mandarin there.
The Thai influence in Tumpat is also amazing.
The people in Trengganu are very friendly and generous.
Overall, a good experience.