It could be economical to buy a direct online starter (DOL) and not use the case. You may need new buttons, a normally open (NO)start button and a normally closed (NC) stop button, usually green and red. Inverter drive supermarket list DOL 230v starters by WEG, you will need to choose the one with the correct overload range for your motor.
Tool station list Starters by IMO and also individual contactors and overloads, rather pricier than the WEG units. To build a motor starter you will need a contactor with a 230V coil, typically it will have 3 normally open contacts (NO) for the load and a (NO)auxiliary for the control circuit, the auxiliary is often just a fourth contact rated the same as the load contacts on a small contactor but on very high power ones the auxiliary will be much smaller rated for control duty only. The overload module should match the contactor as they are designed to fit together but stand alone types are also available. A NO button to start and a NC button to stop is all you require apart from some suitable cable and a circuit diagram. Guard and door switches can be incorporated as well as any extra stop buttons or foot stops that you may desire. There is a choice of buttons available and I would choose a green start button that is flush or below the surrounding shroud, the stop would be red and you have a choice of a simple operator that is above the shroud or small or large mushrooms. If locating new components in the existing space is not possible then the complete starter in its own enclosure can be remotely mounted and just the control buttons connected from their existing position and motor cable rerouted or replaced.
Mike