  We discuss significant improvements to our calculation of electroweak (EW)
$t\bar{t}$ hadroproduction in extensions of the Standard Model (SM) with extra
heavy neutral and charged spin-1 resonances using the Recola2 package. We allow
for flavour-non-diagonal $Z'$ couplings and take into account non-resonant
production in the SM and beyond including the contributions with t-channel $W$-
and $W'$-bosons. We include next-to-leading order (NLO) QCD corrections and
consistently match to parton showers with the POWHEG method fully taking into
account the interference effects between SM and new physics amplitudes. We
briefly describe the Contour method and give some information about the Rivet
repository which catalogues particle-level measurements subsequently used by
Contur to set limits on beyond the SM (BSM) theories. We explain how we use our
calculation within Contour in order to set limits on models with additional
heavy gauge bosons using LHC measurements, and illustrate this with an example
using the leptophobic Topcolour (TC) model.
