First of all you need to work out the designation pattern of your organization. Ex: workmen cadre if Technical - Jr.Tech,Technician, Sr.Technician etc., Production - Jr.Opr, Operator & Sr.Operator etc .
Clerical - start with Asst., Jr.officer, Officer, Sr.Officer, Executive, Sr.Ex, Asst.Mgr followed by the department - Ex- Asst.Manger - Accounts / HR/ Purchase / ware house
similarly
Technical - Asst- Engineering/ production / packing etc., coming to your point it should be Executive - Projects rather than Executive Enginerr - Projects
Considering the criticality pl prepare the designation patter / promotion patter with eligibility creteria / discuss with all HODs, obtain recommendations / approval from CEO / MD / Directors Board. Institutionalize, Communicate to all employees & implement.
The time to bring all changes should be along with annual increments ie., Complete all the formalities maximum by April and issue the increment letters with revised designations. The employees who are not eligible for increments also to be given letters communicating about the change in their designations, if you feel that we need support better to hire a HR consultant so that they can work on the same, implement so it will be easy for you to continue.
Change is painful hence lot of resistance will be there hence you shoud be ready for that. Work out strategies, action plans, identify team members and execute.
I hope you are clear. for any ruther clarifications pl write - kamesh