You can always submit your measurement after placing the order. For now, just select Customize with Made to Measure, click Add to Shopping Bag and complete order. Later on go to Account section, visit My Orders page and submit your latest measurement.
If your bare chest size measurement is 40 inches, you should select size 40 only from the product page. The "Top Chest" attribute in the size chart refers to the garment's chest size. It is inclusive of the required 3 to 4 inches loosening, to ensure the right fit.
If your bare chest measurement falls between 2 sizes i.e 37 inches, you should select size 38.
https://www.utsavfashion.com/product/printed-art-silk-kurta-set-in-teal-blue-mux6431776286Printed Art Silk Kurta Set in Teal Bluehttps://medias.utsavfashion.com/media/catalog/product/cache/1/small_image/295x/040ec09b1e35df139433887a97daa66f/p/r/printed-art-silk-kurta-set-in-teal-blue-v1-mux643.jpg75.294USDInStock/men/men/plus/men/festive/men/art silk/men/blue/men/kurta pyjama/men/floral print/men/resham/men/traditionalPrinted Art Silk Kurta Set in Teal Blue <ul><li> Art Silk Kurta in Teal Blue</li><li> This Readymade Attire is Enhanced with Floral Print and Resham Work. Crafted in Chinese Collar and Full Sleeves</li><li> Available with an Art Dupion Silk Churidar in Beige</li><li> Do note: Footwear shown in the image is for presentation purposes only. Half to one inch may vary in measurement. (Slight variation in actual color vs. image is possible)</li></ul>USDtype_new:Kurta Pyjamacolorfam:Bluefabric:Art SilkBlueArt SilkKurta Pyjama11%-20%MenWithin 15 days, More than 15 DaysReadymadeFestiveMenswearFloral Print, Resham, Traditional34, 36, 38, 40, 4244, 46, 48, 50, 52