Those levers say SLR on them but it is not the same SLR as in current levers. I think those levers are BL-1051 (it will be marked on them, probably you just have not looked hard enough) and have the same pull as other shimano brake levers which are meant for single pivot side pulls.
You can see the marks (just) in this picture
There were several different Ultegra 'tricolour' levers and they work differently and have different lever pull. Ditto 'tricolour' calipers.
Of current shimano levers BL-R400 are pretty close but have a slightly different MA (I think you will get slightly less brake power but you may still find this acceptable). I think older Dia Compe lever designs also have a fairly high MA because they were mostly designed in the days of SP calipers.
cheers