Alternative fuel injection systems and advanced in-cylinder diagnostics are two important tools for engine development; however, the rapid and simultaneous achievement of these goals is often limited by the space available in the cylinder head. Here, a research-oriented cylinder head is developed for use on a single cylinder 2-litre engine, and permits three simultaneous in-cylinder combustion diagnostic tools (cylinder pressure measurement, infrared (IR) absorption, and multi-color pyrometry). In addition, a modular injector mounting system enables the use of a variety of direct fuel injectors for both gaseous and liquid fuels. The design of the all-new cylinder head was derived from a production cylinder head, which was sectioned and laser scanned to create a parametric model. This model was used as the basis for the design and analysis of the new cylinder head and provisions were added to accommodate a modular injector mounting scheme, multiple simultaneous diagnostics, and to reduce intake swirl for imaging purposes. FEA was used to evaluate the mechanical strength and CFD tools were used to optimize cooling, and minimize in-cylinder swirl. The cylinder head was cast in nodular iron, using a 3D-printed sand mold. The functionality and utility of the developed research engine head is demonstrated by presenting cylinder pressure, IR absorption, multi-color pyrometry, spatially-resolved OH*-chemiluminescence, and spatially-resolved natural luminosity measurements of high-pressure direct injection (HPDI) of diesel and natural gas. This paper presents a low-investment, low-risk method for the development of research-oriented cylinder heads with multiple diagnostic accesses and flexible injector mounting.